Systems and methods for providing a tibial baseplate

ABSTRACT

A tibial baseplate is described. While the baseplate can include any suitable component, in some instances, it includes a first surface and a second surface, the second surface being substantially opposite to the first surface and the first surface being configured to be seated on a resected surface at a proximal end of a tibia. In some cases, the baseplate also includes a first spacer coupling that is configured to couple a first spacer to at least one of a lateral side and a medial side of the baseplate such that the spacer is disposed between, and is configured to maintain a set minimal distance between, the proximal end of the tibia and a distal end of a femur when the tibial baseplate is seated on the resected surface at the proximal end of the tibia and the spacer is coupled to the tibial baseplate. Other implementations are discussed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to: U.S. Provisional Patent ApplicationSer. No. 62/572,245, filed Oct. 13, 2017, and entitled “KNEEARTHROPLASTY SYSTEMS AND METHODS” (Attorney Docket No. 7782.58); U.S.Provisional Patent Application Ser. No. 62/518,479, filed Jun. 12, 2017,and entitled “KNEE ARTHROPLASTY SYSTEMS AND METHODS” (Attorney DocketNo. 7782.57); and U.S. Provisional Patent Application Ser. No.62/428,480, filed Nov. 30, 2016, and entitled “KNEE ARTHROPLASTY SYSTEMSAND METHODS” (Attorney Docket No. 7782.55); the entire disclosures ofwhich are hereby incorporated by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to systems and methods that are configuredto provide ligament tensioning, ligament balancing, bone cutting, and/orto otherwise prepare a joint to receive a prosthetic implant duringjoint arthroplasty. In particular, some implementations of the describedsystems and methods provide for ligament tensioning, ligament balancing,and/or bone cutting in a knee joint in preparation for the implantationof one or more femoral and/or tibial prostheses in the knee joint.

2. Description of Related Art

During a knee arthroplasty, a surgeon typically must gain access to theknee joint in order to perform resections of existing bone and cartilageso as to shape the tibia and femur to fit mating surfaces of theimplant. Some arthroplasty procedures seek to minimize the invasivenessof the approach to the knee joint by minimizing the size of the incisionin the surrounding soft tissue structure of the knee and the patella.Preserving the soft tissue structure also preserves some of the supportprovided by these tissues. However, preserving the soft tissuessurrounding the knee can be difficult at times due to the need to firmlysupport the resection guides relative to the bone of the tibia and thefemur.

The manner in which the natural knee joint performs is largely affectedby the tension in the collateral ligaments of the knee, as well as bythe alignment of the articular surfaces of the knee joint relative tothe collateral ligaments. In the natural knee joint, the plane of thearticular surfaces of the femur and the tibia often bisects thecollateral ligaments at an optimal, physiological position. Thisoptimal, physiological position can enable the knee joint to flex andextend in a balanced and properly aligned manner. In some arthroplastyprocedures, resection the femur and the tibia are configured to preservethe optimal, physiological position of the knee joint when fitted with aprosthesis.

Preservation of the ligamentous and other soft tissue structures aroundthe knee can provide a reference point for accurately positioning thetibial and femoral components of the knee implant, in particular whensaid structure is in a tensed or otherwise loaded condition. Forexample, ligament tensions can be used to guide placement of resectionguides. Conversely, preservation of the soft tissue structures requiresbalancing of the forces exerted by the soft tissues to promote normalkinematics in the knee and normal patellar tracking. Therefore, ligamentforces can play a significant role in restoring normal function to aknee. Generally, therefore, reductions in the invasiveness of the kneearthroplasty procedure combined with improvements in the positioning andinstallation of knee components can result in a better overall surgicaloutcome for the patient.

It would therefore be advantageous to have systems and methods forguiding resection of the femur, tibia, and other structures in the kneeduring a knee arthroplasty that works well with minimally invasiveapproaches to the tibia and femur. It would be further advantageous ifthe instrumentation assisted the balancing of forces between the kneeimplant components and the preserved ligamentous and soft tissuestructures for improved function of the knee implant. Also, it would beadvantageous to have instrumentation for guiding resection that uses theligamentous structure of the knee to guide placement of theinstrumentation and the resulting optimal alignment and physiologicalpositioning of the knee prosthesis.

BRIEF SUMMARY OF THE INVENTION

The present invention meets the above needs, and achieves otheradvantages, by providing an assembly for guiding resection of a femurand tibia of a knee joint in preparation for installing femoral andtibial knee components. The components of the present invention may beconfigured for use in both total knee replacement and uni-compartmental,or partial knee arthroplasty.

Some implementations of the present assembly include tibial and femoralintramedullary (IM) rods which are connected through a torque bolt thatallows controlled adjustment of the distraction of the tibia and femurduring cut positioning in a range of flexion angles. Also, someimplementations of such an assembly are usable with relatively small,noninvasive approaches to the knee joint by way of relatively narrow,low profile components that attach to tibial and/or femoral IM rods.Further, some implementations of such an assembly include severalquick-release components to allow fast assembly and disassembly in asurgical setting. Each of these aspects, along with the ability of theassembly to accurately guide initial reference cuts to the tibia andfemur, can promote an improved outcome for the patient.

An assembly of one implementation of the present invention includesfemoral and tibial IM rods, a flexion cutting guide, an extensioncutting guide, and a selection of selectively lockable components. Eachof the IM rods in such implementation includes a shaft portion that isconfigured to extend within the IM canal of the femur or tibia. Someimplementations of the femoral IM rod also include a femoral mount on anend of the shaft that is configured to extend away from the femur whenthe shaft is in the femoral IM canal. Similarly, some implementations ofthe tibial IM rod include a tibial mount on an end of the shaft that isconfigured to extend away from the tibia when the shaft is in the tibialIM canal. In some implementations, each of the mounts is configured toattach to one or more of the selectively lockable components. Theflexion and extension cutting guides of some such implementations defineone or more slots wherein the slots are configured to guide the use ofcutting and other instruments to make preparatory cuts to the femurand/or the tibia with the knee in flexion and extension. Each of thecutting guides is configured, in accordance with some implementations,to attach to one or more of the selectively lockable components so as tobe supported by the femoral and tibial IM rods. The selectively lockablecomponents are configured, in at least some implementations, to attachto the femoral and tibial IM rods, to have at least one portion with arelatively small cross section extending anteriorly or anterior-medialout of the knee joint compartment and to attach to the flexion andextension cutting guides and support and limit the motion thereof.

In one aspect, the femoral mount has a cylindrical shape that extends inan anterior-posterior direction between the femoral condyles andincludes a central opening and a plurality of gauge marks extendingalong its outside surface. The central opening may also include ananterior anti-rotation portion (e.g., a hexagonal shaped portion) and alarger diameter cylindrical portion. The tibial mount can include orsupport a flexion bolt with a threaded shaft at one end configured toextend into an opening in the tibial IM shaft, a bushing at the otherend and an exterior hexagonal flange in between the ends. The bushing isconfigured to extend into the cylindrical portion and also contains aninterior hexagonal bore. The hexagonal flange is configured to allowgripping by an external torque wrench or internal torque driver to urgethe femoral mount away from the tibial mount (by turning of the threadedshaft) and distract the tibia and femur to a desired torque reading.This allows the surgeon to apply the appropriate amount of tension tothe ligamentous structure as defined by said surgeon and recorded forcomparison later in the technique.

Included in at least one implementation of the selectively lockablecomponents is a first locking mechanism that has an arm, a plungerassembly and an anti-rotation extension, defined in this instance as ahex. The arm has an elongate portion extending away from a head portion.Also extending from the head portion is the hex-shaped anti-rotationextension. Defined through the head portion and hex extension is anopening that is configured to receive a shaft of the plunger assembly.The plunger assembly includes a thumb press at one end of the shaft andan anti-rotation feature similar to anti-rotation extension, defined inthis instance as a hexagonal tip at the other end of the shaft thatextends out of the hex extension. Also, the shaft includes a peg thatextends into a helically shaped slot defined in the head portion. Aspring extends between the head portion and the thumb press. Depressionof the thumb press advances the shaft, while the peg and helical slotcause the shaft to rotate, and the flats of the hexagonal tip to alignwith the hex extension. This allows the hexagonal tip and hex extensionto become concentric and to be inserted into the anterior hex portion ofthe central opening of the femoral mount. In addition, the hexagonal tipis configured to extend out of the hex portion of the opening and intothe cylindrical portion, and to rotate (due to the helical slot and peg)into an eccentric position upon release of the thumb press, therebylocking the locking mechanism into the femoral mount. When attached, thehead portion of the arm extends proximally out of the knee jointcompartment and the elongate portion extends anteriorly (with respect tothe tibia) through the surgical incision.

At least some implementations of a flexion guide support member of theassembly of the present invention include a slider member and a ratchetbar. The slider member is configured to attach to, and slide along, theelongate portion of the arm of the first locking mechanism, such as byhaving an opening defined therein matching the cross-section of theelongate portion. The ratchet bar is configured to extend toward a planedefined by the tibial plateau. Preferably, when assembled, the femoralmount, first locking mechanism and flexion guide support member roughlyform a U-shape that is relatively narrow in the medial-lateral directionto allow its use with narrow incisions.

Also included in some implementations of the selectively lockablecomponents is a quick release mechanism that is configured to slidealong and lock to the ratchet bar of the flexion guide support member.For example, the quick release mechanism may define an openingconfigured to extend and slide along the ratchet bar, and a locking pinthat is spring loaded to extend into a portion of the ratchet to stopthe sliding motion. The locking pin is spring biased, but can beovercome with a manual draw pull (for example) to allow further slidingor repositioning of the quick release mechanism. The quick releasemechanism may also include a spring-biased locking lever that, alongwith an engagement member of the quick release mechanism, can extendinto an opening and lock to the flexion cutting guide. Depressing thelocking lever again easily releases the flexion cutting guide afterk-wire or other fasteners have been used to secure the flexion cuttingguide in place to the tibia or femur. This allows the resection guide totranslate toward the proximal tibia and away from the tensioningassembly with the knee in flexion.

Once the flexion resection guide is fixed to the proximal tibia, theresection guide has a plurality of slots for which to resect multiplecomponents of the femur and tibia, most notably a measured proximaltibial resection and a posterior condylar resection. Making theseresections with the knee in tension at 90 degrees will allow the user totheoretically make a tensed flexion gap resection.

The selectively lockable components may also include componentsconfigured to attach to the femoral and tibial IM rods when the knee isin extension. For example, the components may include a cannulatedextension bolt, a tibial angulation guide, an extension guide supportmember and a second locking mechanism. The tibial angulation guide isconfigured to attach to the tibial IM rod through the cannulatedextension bolt which is, in turn, coupled to the tibial IM rod andextend around the femoral mount, such as by having a block defining anarc-shaped channel that is configured to receive the cylindrical outersurface of the femoral mount. Included on the tibial angulation guideare a plurality of gauge marks that, when correlated to gauge marks onthe outer surface of the femoral mount, register an amount of valgusangulation of the tibia with respect to the femur. The tibial angulationguide may be configured to extend into the bushing of the bolt describedabove, or to have its own threaded shaft and hexagonal flange allowingit to be used to distract the tibia and femur in extension to a torquevalue corresponding to the torque value previously measured with theknee in flexion.

At least some implementations of the extension guide support member areconfigured to have a relatively narrow profile and extend anteriorly outof the joint compartment through the incision providing access thereto.For example, the extension guide support member may include a mountingportion that is cylindrical and defines a cylindrical opening and asupport arm that is configured to extend proximally from the mountingportion. The second locking mechanism is generally configured similar tothe first, except it lacks the fixed elongate portion of the arm.Rather, it includes a cylindrical head portion that is configured toextend through the cylindrical opening of the mounting portion of theextension guide support member so as to connect the extension guidesupport member to the femoral mount while allowing said support memberto rotate in a desired position independent of the previously selectedvalgus angle.

Some implementations of the extension guide support member also includea support arm that is configured to extend proximally from the mountingportion when the mounting portion is attached to the femoral mount usingthe second locking member. The extension cutting guide is configured toslidably attach over the support arm, such as via a channel defined inits body. Also, the extension cutting guide preferably includes a swivelarm that can be swung into an abutting relationship with the tibialplateau and the plateau flange of the tibial mount to provide anadditional reference point for making a femoral resection with the kneein extension. The extension cutting guide, similar to the flexioncutting guide, may also define a plurality of fixation openings allowingfasteners to extend there-through and attach the extension cutting guideto the tibia or femur. This allows removal of the selectively lockablecomponents to provide room for the cuts to the tibia and/or the femur.

The swivel arm, once referenced off the proximal tibial resection, will(in accordance with some implementations) allow the extension cuttingguide to make a pre-determined resection of the distal femur. Resectingwith the knee tensed in the extended position will allow the user tomake a balanced extension gap resection when compared with the tensedresections made with the knee previously positioned in flexion.

The aforementioned assembly of the present invention has manyadvantages. For example, it provides a relatively narrow and low profilecollection of locking components that securely attach cutting guides totibial and/or femoral IM rods. This provides a robust guide to referencecuts being made to the tibia and the femur with an approach to the jointthat minimizes invasiveness. Further, many of the components, such asthe first and second locking mechanisms and the quick release mechanism,facilitate quick assembly, easy adjustment and quick disassembly forimproved efficiency. Additionally, the use of the flexion bolt inflexion and the extension bolt in extension, combined with the othercomponents of the tensioning assembly, allow the tibia and femur to bedistracted under a matching amount of tension in flexion and extensionto ensure a better fit for the tibial and femoral knee replacementcomponents throughout a range of flexion. In accordance with someimplementations, spacers, as well as limited radial movement of thetensioning assembly components, further allow the knee to adjust toaccommodate the natural physiology of the patient's knee throughout thetensioning and resection processes. Thus, the described procedures andassemblies allow the surgeon to adjust the amount of varus-valgusangulation of the tibia as desired to match the anatomy of the patient.

In addition to the foregoing, some implementations of the describedsystems and methods relate to systems and methods for preparing a kneefor resection, as well as for guiding preparation of a knee forinstallation of an implant during an arthroplasty. In particular, someimplementations of the present invention relate to a system for guidinga milling tool along a specific axis to provide an aperture of a desireddepth, prior to resection.

An implementation of such a system includes a bone milling system havinga milling tool member and a guide rod. The guide rod is partiallydeposited within the intramedullary (IM) canal of the bone, and aportion of the guide rod extends outwardly from the IM canal along adesired axis. The exposed portion of the guide rod is adapted torotatably insert within a cavity of the milling tool member. As such,the milling tool member is guided along the desired axis by the exposedportion of the guide rod.

The milling tool member includes a cutting head portion and a shaft. Inaccordance with some implementations, the cutting head potion includes ablade having a cutting edge and a window. The cutting edge cuts theaperture into the bone, and the window provides an escape route for theremoved bits of bone debris. A cavity is also provided running throughthe shaft and cutting head portion. The cavity is generally tube shapedhaving an open end and a closed end. The open end is in fluidcommunication with an opening in the blade. The closed end includes ashank for coupling the milling tool member to a drill or other devicefor rotating the member.

Following creation of the aperture, a resection block is combined withthe bone milling system to resect the bone. In some implementations, theaperture is first made in the tibia and then used as a reference pointand/or mounting surface for tensioning the knee and making resections tothe exposed femur. In other implementations, the aperture is first madein the tibia and then used as a reference point and/or mounting surfacefor positioning a resection block to resect the tibia. Other embodimentsof the present invention include a bone milling device that incorporatesa guide rod, a cutting surface and a shank into a singular unit.

In addition to the foregoing, some implementations of the describedsystems and methods further include one or more wedges and/or otherspacers that are configured to be inserted in between a femur and atibia in a knee joint to apply tension to one or more of the kneejoint's ligaments/tendons (e.g., the collateral ligaments and/or anyother suitable ligaments), to balance ligament tension in the kneejoint, to properly align the tibia and/or femur for resection, tosupport and/or to otherwise place a cutting guide block in a desiredposition, and/or to otherwise prepare the knee joint for resectionand/or implantation of one or more prostheses.

With respect to the spacers, the spacers can have any suitablecharacteristic that allows them to function as described herein. Indeed,the spacers can be any suitable shape, including, without limitation,being wedged shaped, cup shaped, dish shaped, and/or any other suitableshape. Additionally, the spacers' external surface can have any suitabletexture that allows the spacers to function as intended. In someimplementations, the spacer includes one or more smooth surfaces thatallow a portion of the femur and/or the tibia to articulate against thespacer as the knee joint is moved through its range of motion. Indeed,in some implementations, a proximal side of the spacer comprises asmooth articular surface that is configured to allow a distal end of thefemur to articulate against it as the knee joint moves through a rangeof motion.

Also, while some implementations of the spacers comprise a flat and/orangled surface that is configured to contact at least one of the femurand the tibia when the spacer is inserted in the knee joint, in someother embodiments, the spacer comprises a recessed portion (e.g., adish-like and/or concave surface) that is configured to cradle a portionof at least one of the tibia and the femur. In some implementations,however, one or more of the spacers comprise a substantially rectangularcuboidal (or prism) shape. In some embodiments, one or more ends of suchspacers (e.g., a posterior end that is configured to be disposedposteriorly within a knee joint) are optionally notched, rounded,angled, wedge-shaped, and/or otherwise shaped to allow such spacers toeasily be slid in between (and/or to separate) the femur from the tibia.

In some other implementations, the spacer comprises one or morenon-smooth surfaces. Some non-limiting examples of such non-smoothsurfaces include one or more surfaces comprising one or more roughenedtextures, spongiosa metals (and/or other material), knurled textures,barbs, ridges, processes, zig-zag surfaces, cog-like surfaces, porouscladding, external frames, pins, and/or any other suitable surfaceand/or component that is configured to help prevent the spacer fromsliding out from between the femur and tibia.

Although, in some implementations, each spacer comprises a singlemonolithic object, in some other implementations, each spacer comprisesmultiple components. Indeed, in some embodiments, the spacer comprises aproximal portion that is configured to contact a distal portion of thefemur and a distal portion that is configured to contact a proximalportion of the tibia when the spacer is inserted into the knee joint. Insome such implementations, the spacer comprises one or more springs(and/or other resilient materials) that are configured to force (orbias) the distal and proximal portions of the spacer apart so as toapply a consistent and/or constant pressure to the femur and the tibiawhen the spacer is inserted into the knee joint.

In some implementations, the spacer further comprises one or moremechanisms for measuring a pressure that is placed on the spacer as itis placed in the knee joint. Accordingly, in some implementations, whena first spacer is placed in a lateral side of the knee joint and asecond spacer is placed in a medial side of the knee joint, apractitioner and/or computer device can determine whether or not tensionin the knee joint is balanced.

In some implementations, the spacer is configured to be used with anysuitable conventional and/or novel method of joint arthroplasty. In someother implementations, however, the spacer is configured to be used withone or more of the apparatuses, systems, and/or methods describedherein. Indeed, in some implementations, one or more spacers areconfigured to adjustably couple to one or more of the componentsdescribed herein, including, without limitation, to the tibial mount,the tibial component, the femoral mount, the tibial tensioning adapter,and/or any other suitable component that allows the spacer to beselectively held in place while the spacer is disposed in the kneejoint.

Although in some implementations, the spacer comprises no handle, insome other implementations, the spacer comprises one or more handlesthat are configured to help a user readily manipulate the spacer, evenwhen the spacer is disposed in the knee joint. While in some cases, ahandle is permanently coupled with a spacer, in some other embodiments,the spacer and a corresponding handle are configured to selectivelycouple to and/or decouple from each other in any suitable manner,including, without limitation, by having a projection at an end of thehandle fit into a recess at an anterior portion (and/or any othersuitable portion) of the spacer, via one or more catches, one or moremagnets and/or magnetic materials disposed in the handle and the spacer,and/or in any other suitable manner. Indeed, in some implementations, ananterior portion of the spacer (or a portion that is configured to bedisposed towards an anterior portion of the knee joint when the spaceris disposed between the tibia and the femur) defines a recess that isconfigured to receive a projection at an end of the handle. In some suchembodiments, the handle's projection comprises a raised member that isconfigured to extend into a corresponding opening in the recess of thespacer (e.g., when the handle is disposed at a certain angle) such thatthe handle can be used to pull the spacer from between the tibia and thefemur.

In addition to the aforementioned features, some implementations of thedescribed systems and methods comprise one or more articulatedconnections that extend between the described tibial and femoralcomponents to allow a knee joint with such components to move through arange of motion without requiring a user to change between a 0 degreeextension adapter and a 90 degree flexion adapter. In suchimplementations, the articulated connection can comprise any suitablecomponent, including, without limitation, a femoral component, a tibialcomponent, a tibial angulation guide, an extension bolt, a ratchetingdevice, and/or any other suitable component that comprises a joint andthat is configured to couple (directly or indirectly) with a tibialcomponent and a femoral component to maintain a desired tension in theknee joint while allowing the knee joint to flex and/or extend.

In some implementations, the described apparatuses and/or systemsfurther comprise one or more soft tissue retractors and/or laminaspreaders. Indeed, in some implementations, one or more soft tissueretractors are attached to any suitable portion of the describedapparatuses and/or systems. Accordingly, in some such implementations,one or more soft tissue retractors are coupled to (e.g., permanently,selectively, adjustably, and/or otherwise), formed on, and/or otherwiseassociated with one or more of the femoral mount, a femoral component,the tibial mount, a tibial component, a tensioning assembly, a cuttingblock, the spacers and/or any other suitable portion of the describedapparatuses and/or systems to provide better exposure to the bones inthe knee joint while the described systems and methods are in use.

In some implementations, the described systems and apparatuses furtherinclude one or more tibial baseplates. In such implementations, thetibial baseplate can perform any suitable purpose, including, withoutlimitation, providing a guide for driving a keel punch into a proximalend of a tibia; coupling with, guiding, and/or holding the spacers inplace; coupling with a tensioning assembly to allow the tensioningassembly to press against the tibial baseplate to when adjusting thedistance between the tibia and the femur via actuation of the tensioningassembly; coupling with, guiding, and/or maintain a position of one ormore trial tibial components; and/or for any other suitable purpose.

Indeed, in some embodiments, the tibial baseplate has a first surfaceand a second surface that is substantially opposite to the firstsurface, the first surface being configured to be seated on a resectedsurface at a proximal end of a tibia. In some such implementations, thetibial baseplate further defines a keel punch guide which includes afirst wing that is configured to extend over a lateral portion of the ofthe proximal end of the tibia and a second wing that is configured toextend over a medial portion of the proximal end of the tibia when thetibial baseplate is seated on the resected surface at the proximal endof the tibia.

In some implementations, the tibial baseplate has a first surface and asecond surface that is substantially opposite to the first surface, thefirst surface being configured to be seated on a resected surface at aproximal end of a tibia, wherein the tibial baseplate comprises a firstspacer coupling that is configured to couple a first spacer to at leastone of: a lateral side and a medial side of the tibial baseplate suchthat the first spacer is disposed between, and is configured to maintaina set minimal distance between the proximal end of the tibia and adistal end of a femur when the tibial baseplate is seated on theresected surface at the proximal end of the tibia and the first spaceris coupled to the tibial baseplate.

In still other implementations, the tibial baseplate has a first surfaceand a second surface that is substantially opposite to the firstsurface, the first surface being configured to be seated on a resectedsurface at a proximal end of a tibia, the tibial baseplate including: afirst spacer coupling that is configured to couple a first spacer to alateral side of the tibial baseplate such that the first spacer isdisposed between, and is configured to maintain a set minimal distancebetween the lateral side of the tibial baseplate and a lateral side of adistal end of a femur when the tibial baseplate is seated on theresected surface at the proximal end of the tibia and the first spaceris coupled to the first spacer coupling; and a second spacer couplingthat is configured to couple a second spacer to a medial side of thetibial baseplate such that the second spacer is disposed between, and isconfigured to maintain a set minimal distance between the medial side ofthe tibial baseplate and a medial side of the distal end of the femurwhen the tibial baseplate is seated on the resected surface at theproximal end of the tibia and the second spacer is coupled to the secondspacer coupling.

In addition to the foregoing, some implementations of the describedsystems and methods involve the use of one or more robots. In thisregard, the robots can perform any suitable function, including, withoutlimitation, using the milling tool member to resect a portion of thetibia (e.g., with and/or without the guide rod), to resect a proximalend of the tibia, to resect one or more portions of a distal end of thefemur (e.g., to make a distal cut, an anterior cut, a posterior cut, ananterior chamfer cut, a posterior chamfer cut, and/or any other suitablecut). Indeed, in some implementations, the described systems and methodsare further configured to allow one or more robots to resect portions ofthe knee joint while one or more of the described apparatuses and/orsystems are disposed in and providing a desired ligamentous tension inthe knee joint.

While the methods and processes of the present invention have proven tobe particularly useful in the area orthopedics, those skilled in the artcan appreciate that the methods and processes can be used in a varietyof different applications and in a variety of different areas ofmanufacture to yield functionally equivalent results.

These and other features and advantages of the present invention will beset forth or will become more fully apparent in the description thatfollows and in the appended claims. The features and advantages may berealized and obtained by means of the instruments and combinationsparticularly pointed out in the appended claims. Furthermore, thefeatures and advantages of the invention may be learned by the practiceof the invention or will be obvious from the description, as set forthhereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In order that the manner in which the above recited and other featuresand advantages of the present invention are obtained, a more particulardescription of the invention will be rendered by reference to specificembodiments thereof, which are illustrated in the appended drawings. Thedrawings depict only typical embodiments of the present invention andare not, therefore, to be considered as limiting the scope of theinvention. Additionally, any measurements provided in the drawings aresimply provided as possible examples, noting that all such measurementscan adjusted in any suitable manner and that such measurements in no waylimit the scope of the invention. Accordingly, the present inventionwill be described and explained with additional specificity and detailthrough the use of the accompanying drawings in which:

FIG. 1 is a plan view of a tibial intramedullary (IM) rod and femoral IMrod of an assembly of one embodiment of the present invention;

FIG. 2 is a perspective view of the femoral IM rod of FIG. 1 insertedinto a femur;

FIG. 3 is a cross-section of a femoral mount of the femoral IM rod shownin FIG. 2;

FIG. 4 is a perspective view of a femoral and tibial IM rods of FIG. 1inserted in the femur and tibia of a knee, respectively;

FIG. 5 is a perspective view of a bushing extending from an extensionbolt of the assembly of the present invention wherein the extension boltis coupled to the tibial IM rod of FIG. 1;

FIG. 6 is a plan view of the extension bolt of FIG. 5 and of a tibialangulation guide and flexed knee cutting guide of the assembly of thepresent invention;

FIG. 7 is a perspective view of the bushing and IM rods of FIG. 5,wherein the bushing of the extension bolt is advanced to connect the IMrods;

FIG. 8 is a side elevation view of a first locking mechanism of theassembly of the present invention;

FIG. 9 is a perspective view of the first locking mechanism beingconnected to the assembled IM rods and bolt of FIG. 7, torqued to adesired load;

FIG. 10 is another perspective view of the first locking mechanism inthe unlocked position, assembled IM rods and bolt of FIG. 9, torqued toa desired load;

FIG. 11 is yet another perspective view of the first locking mechanismassembled and locked to the IM rods and extension bolt of FIG. 9,torqued to a desired load;

FIG. 12 is a perspective view of a flexion guide support member of theassembly of the present invention connected to the first lockingmechanism of FIG. 11;

FIG. 13 is a perspective view of a flexed knee cutting guide assembly ofthe assembly of the present invention connected to the flexion guidesupport member of FIG. 12;

FIG. 14 is a side elevation view of the assembly of FIG. 13;

FIG. 15 is a rear elevation view of the assembly of FIG. 13;

FIG. 16 is a bottom elevation view of a quick release mechanism of theflexed knee cutting guide assembly of FIG. 13;

FIG. 17 is a perspective view of the quick release mechanism of FIG. 16and the flexion guide support member of FIG. 12;

FIG. 18 is a perspective view of a flexed knee cutting guide of theflexed knee cutting guide assembly of FIG. 13;

FIG. 19 is a front elevation view of a tibial angulation guide of theassembly of the present invention extending between the femoral andtibial IM rods of FIG. 1, coupled with an extension bolt;

FIG. 20 is an enlarged view of the IM rods and tibial angulation guideof FIG. 19;

FIG. 21 is another enlarged view of the IM rods and tibial angulationguide of FIG. 19;

FIG. 22 is a perspective view of a second locking mechanism andextension guide support member of the assembly of the present inventionbeing assembled to the femoral IM rod of FIG. 1;

FIG. 23 is an enlarged perspective view of the assembly of the extensionguide support member of the present invention to the second lockingmechanism of FIG. 22;

FIG. 24-26 are various a perspective views of an extended knee cuttingguide of the assembly of the present invention attached to the extensionguide support member and second locking mechanism of FIG. 22, and thefemoral IM rod of FIG. 1;

FIG. 27 is a perspective view illustrating disassembly of the secondlocking mechanism of FIG. 22, from the femoral IM rod of FIG. 1, oncethe extended knee cutting guide is fixed in position to the distalfemur;

FIG. 28 is a front elevation view of the extended knee cutting guide ofFIG. 24;

FIG. 29 is a side elevation view of the extended knee cutting guide ofFIG. 24;

FIG. 30 is a plan view of an L-shaped cutting block of the assembly thepresent invention;

FIG. 31 is a side elevation view of the L-shaped cutting block of FIG.30 being used to cut an anterior condyle of a femur;

FIGS. 32-40 show various modular options of the present invention thatpromote quick assembly and facilitate minimally invasive intra-operativeuse;

FIG. 41 shows a hinged retractor as used in one embodiment of thepresent invention;

FIGS. 42A-42E shows an embodiment of the present invention thatimplements mini-trials;

FIG. 43 shows an exploded view of an embodiment of the present inventionfor resection in knee flexion;

FIG. 44 shows a perspective view of the assembled embodiment of FIG. 43;

FIG. 44A shows a perspective view of an implementation of the currentinvention having a ratcheting device in place of the flexion bolt;

FIG. 45 shows a perspective view of an embodiment of the presentinvention having the cutting block attached and secured;

FIG. 46 shows an exploded view of an embodiment of the present inventionfor resection in knee extension;

FIG. 47 shows a perspective side view of the assembled embodiment ofFIG. 46;

FIG. 48 shows a perspective view of an embodiment of the presentinvention having the cutting block attached and secured;

FIG. 49 shows a perspective front view of an embodiment of theresectioned knee having been fitted with a knee prosthesis;

FIG. 50 shows a perspective side view of the embodiment of FIG. 49;

FIG. 51 shows a partially cross-sectioned view of an implementation ofthe knee prosthesis;

FIGS. 52A-52C illustrate some embodiments of articulated connectors;

FIG. 53 is a perspective view of a representative embodiment of thepresent system as incorporated into a knee, shown in phantom;

FIG. 54 is a cross-sectioned view of a representative embodiment of thepresent system prior to formation of an aperture;

FIG. 55 is a cross-sectioned view of a representative embodiment of thepresent system following formation of an aperture, demonstrating use ofa depth gauge;

FIG. 56 is a cross-sectioned view of a representative embodiment of thepresent system following formation of an aperture;

FIG. 57 is a cross-sectioned view of a representative embodiment of thepresent system incorporating a resection block;

FIG. 57A is a perspective view of a representative embodiment of aresection block having a plurality of adjustments and apertures;

FIG. 57B is a cross-sectioned view of a representative embodiment of aresection block system coupled to a portion of the guide rod;

FIG. 58 is a perspective view of a representative embodiment of themilling bit;

FIG. 59 is a perspective view of a representative embodiment of themilling bit;

FIG. 60 is a perspective view of a representative embodiment of the bonemilling device as embodied in a singular unit;

FIG. 61 illustrates a side view a bone milling device being used with anautomated device in accordance with some embodiments;

FIGS. 62A-R, 63A-H, 64A-D, 65A-I, 66A-B, 67A-C, 68A-H, 69A-F, and FIG.70 illustrate various embodiments of the described systems and methods;

FIGS. 71A-B, 72A-B, and 73A-C illustrate various embodiments of a tibialbaseplate;

FIG. 74A illustrates a perspective of the tibial baseplate and a trialtibial component in accordance with a representative embodiment;

FIGS. 74B-C and 75A-C illustrate various views of the trial tibialcomponent and/or the tibial baseplate in accordance with someembodiments;

FIG. 75D depicts a perspective view of a knee joint in extensioncomprising the tibial baseplate and the trial tibial component inaccordance with a representative embodiment;

FIG. 75E depicts a perspective view of a knee joint in flexioncomprising the tibial baseplate and the trial tibial component inaccordance with a representative embodiment;

FIG. 76A depicts a perspective view of a knee joint in flexioncomprising multiple spacers in accordance with a representativeembodiment;

FIG. 76B depicts a perspective view of a knee joint in extensioncomprising multiple spacers in accordance with a representativeembodiment;

FIG. 76C depicts a perspective view of a knee joint in flexioncomprising a cutting block reference spacer in accordance withrepresentative embodiment;

FIG. 76D depicts a perspective view of a knee joint in flexioncomprising the cutting block reference spacer and a cutting block inaccordance with representative embodiment;

FIG. 76E depicts a perspective view of a knee joint in extensioncomprising the cutting block reference spacer in accordance withrepresentative embodiment;

FIG. 76F depicts a perspective view of a knee joint in extensioncomprising the cutting block reference spacer and the cutting block inaccordance with representative embodiment;

FIGS. 76G-76H illustrate some embodiments of arthroplasty kits;

FIG. 77A depicts a front view of a knee joint in flexion comprising twolamina spreaders in accordance with a representative embodiment;

FIG. 77B depicts a front view of a knee joint in extension comprisingtwo lamina spreaders in accordance with a representative embodiment;

FIG. 77C depicts a side perspective view of a knee joint in flexion, theknee joint comprising two lamina spreaders, the cutting block referencespacer, and the cutting block in accordance with a representativeembodiment;

FIG. 77D depicts a side perspective view of a knee joint in extension,the knee joint comprising two lamina spreaders, the cutting blockreference spacer, and the cutting block in accordance with arepresentative embodiment;

FIGS. 77E-77F depict a portion of a spreading device comprising aprocess that is configured to be received within a portion of a tibialbaseplate in accordance with some representative embodiments;

FIG. 78 depicts a representative embodiment of a kit for preparing aknee joint for partial and/or full knee replacement in accordance withsome embodiments;

FIG. 79 depicts a view of the tibial baseplate comprising multiplespacers and a handle that is configured to push the spacers into adesired location;

FIGS. 80, 81, 82A-82B depict some embodiments of the described systemsused in conjunction with the tibial baseplate;

FIG. 83 depict some embodiments of a bone milling kit; and

FIGS. 84A-84B depict some embodiments in which the tibial baseplate isconfigured to guide a punch into a tibia.

DETAILED DESCRIPTION OF THE INVENTION

Reference throughout this specification to “one embodiment,” “anembodiment,” “an implementation,” and similar language means that aparticular feature, structure, or characteristic described in connectionwith the embodiment or implementation is included in at least oneembodiment of the present invention. Thus, appearances of the phrases“in one embodiment,” “in an embodiment,” “in another embodiment,” “insome implementations,” “in some other embodiments,” “in some otherimplementations,” and similar language throughout this specificationmay, but do not necessarily, all refer to the same embodiment orimplementation.

The present invention now will be described more fully hereinafter withreference to the accompanying drawings, in which some, but not allembodiments of the invention are shown. Indeed, this invention may beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will satisfy applicable legalrequirements. Like numbers refer to like elements throughout.

The following disclosure of the described systems and methods is groupedinto three subheadings, namely “Representative Systems and Methods”,“Bone Milling”, and “Spacers and Baseplate”. Utilization of thesubheadings is for convenience of the reader only and is not to beconstrued as limiting in any sense.

Representative Systems and Methods

An assembly 10 of the present invention for facilitating preparation ofa knee joint, including guiding positioning of cuts to a femur 11 andtibia 12 of the knee joint, for later mating with femoral and tibialknee replacement components, is shown in the accompanying figures.Generally, the assembly 10 includes various components selected andarranged to attach to a reference point inside the knee jointcompartment (such as one or more intramedullary (IM) rods), extendthrough a relatively narrow, small or noninvasive approach defined inthe soft-tissues of the knee and attach outside the knee to a selectionof resection guides.

Anatomical directions as used herein are in reference to the knee duringthe preparatory surgery and correspond to the illustrated embodiment ofthe assembly 10. However, depending upon the handedness of the knee, orvariations in individual morphology and ligamentous structure, thesedirections could vary and should not typically be considered limiting.

The assembly 10 can be configured to be applied at different kneeflexion angles to facilitate positioning of the components throughoutthe range of flexion or extension. Illustrated herein are components ofthe assembly 10 for guiding cuts and preparation of the knee at twodifferent flexion angles, namely 90° and full extension. However, thecomponents can be adjusted or configured, or other components employedwithin the spirit and scope of the present invention, to extend throughrelatively non-invasive approaches to the knee joint at any range offlexion be it hyper-extension, 30°, 45°, 60°, etc., through tohyper-flexion.

In the illustrated embodiment, the assembly 10 includes two IM rods, afemoral IM rod 13 and a tibial IM rod 14 that provide a reference pointfor supporting the remainder of the assembly 10 with the knee inflexion, in this case 90° of flexion. The femoral IM rod 13 includes afemoral mount 15 and a main shaft 16, as shown in FIG. 1. The main shaft16 of the femoral IM rod 13 is preferably an elongate, relatively rigidshaft that, when installed, extends within the IM canal of the femur 11in a proximal-distal direction, as shown in FIG. 2. The main shaft 16can include structure that facilitates its insertion into the femur 11,such as a tapered end 17. Preferably, the main shaft 16 is constructedof a relatively rigid material, such as a hard plastic, stainless steel,titanium or other metal or material that is capable of insertion intobone without damage and of stably supporting the femoral mount 15.

Attached to the distal end of the main shaft 16, opposite the taperedend 17, is the femoral mount 15. Generally, the femoral mount has acylindrical shape with an axis extending perpendicular to a long axis ofthe main shaft 16. Defined along the axis of the femoral mount 15 is acentral opening 18, as shown by the cross-sectional view of the femoralmount in FIG. 3. The central opening includes two portions, ananti-rotation portion, in this instance a hex portion, 19 and acylindrical portion 20 which allow locking of other components of theassembly 10 to the femoral mount 15, as will be described in greaterdetail below. Regardless, once the femoral IM rod 13 is installed, thefemoral mount 15 and its central opening 18 preferably extend in ananterior-posterior direction along the femoral notch between the femoralcondyles. Defined on the outer cylindrical surface of the femoral mount15 is a plurality of longitudinally extending gauge marks 21 that aid inpositioning of the tibial and femoral components, as will be describedin more detail below.

As shown in FIGS. 1 and 4, the tibial IM rod 14 includes a main shaft 22supporting a tibial mount 23. Similar to the main shaft 16 of thefemoral IM rod 13, the main shaft 22 has an elongate structure with atapered distal end 24 to facilitate its insertion into the IM canal ofthe tibia. However, the main shaft 22 preferably includes one or moreflutes 25 extending along its length in order to further facilitateinsertion and to resist rotation within the IM canal of the tibia. Theseflutes may also, optionally, be included on the main shaft 16. Definedin the main shaft 22 at its proximal end is an opening 27 that extendsinto the flutes 25. These openings further facilitate insertion into theIM canal of the tibia. As with the main shaft 16 of the femoral IM rod13, the main shaft 22 may be constructed of a range of relatively rigidmaterials to provide firm support for the tibial mount 23. In someembodiments of the current invention, the main shaft 22 of the tibial IMrod is truncated to form a short extension for engaging an opening inthe upper surface of the tibia. As such, the tibial IM canal is notaccessed but rather the tibial mount 23 and the truncated tibial IM rodprimarily engage and interface with the external surface of the tibia.In other embodiments, the tibial mount 23 is provided without a tibialIM rod, such that a flat surface of the tibial mount 23 seats directlyon the resectioned surface of the tibia. As such, the interface betweenthe tibial mount 23 the tibia is completely extramedullary. In theseembodiments, the position of the tibial mount 23 with respect to thetibia is maintained by the perpendicular compression force between thetibial mount 23 and the tibia. In other embodiments, the flat surface ofthe tibial mount 23 is modified to include a plurality of spikes whichfurther interface with the resectioned tibial surface to preventundesirable movement of the tibial mount component 23 during tensioning.

Included in the tibial mount 23 are a thickened cylindrical portion 26and a plateau flange 28, as shown in FIG. 4. The cylindrical portion 26is preferably sized to fit the IM canal of the tibia 12. The cylindricalportion is connected at its distal end to the main shaft 22 and at itsproximal end supports the plateau flange 28. The plateau flange extendsoutward at right angles from the cylindrical portion 26 and has threeflat sides and one crescent-shaped side. The crescent shaped side is acutout to provide room for the anterior cruciate ligament prior toresection of the proximal tibia. The flat sides can further aid in guidepositioning and cutting, such as during a tibial compartmental resectionin a unicondylar arthroplasty procedure wherein only a single condyleand a portion of the tibial plateau are reconstructed.

A threaded opening 29 extends into the tibial mount 23 and provides acoupling attachment for the flexion bolt 30, which includes a threadedshaft 31, a hex flange 32 and a bushing 33, as shown in FIGS. 5 and 6.The threaded shaft 31 has a plurality of threads and extends away fromthe hex flange 32, while the bushing 33 is a smooth, cylindrical shaftthat extends opposite the threaded shaft from the other side of the hexflange 32. The hex flange 32 is shaped to allow gripping by a torque orother wrench to provide motivation for advancement of the threaded shaft32.

The threaded shaft 31 is configured to be advanced into the threadedopening 29 of the tibial mount 23 until it is flush with the plateauflange 28 thereby positioning the bushing 33 at its lowest profileposition, as shown in FIG. 5. This position allows the femur 11 andfemoral mount 15 extending therefrom to be slipped into position abovethe bushing 33. Then, the torque wrench is used to reverse theadvancement of the threaded shaft 31 until the bushing 33 engages thecylindrical portion 20 of the central opening 18 in the femoral mount15, as shown in FIG. 7. Advancement is reversed until a pre-selectedtorque measurement is reached on the torque wrench, or adequate tensionof the ligamentous structure is obtained. Once the appropriate ligamenttension is obtained, this torque value is recorded for comparison laterin the technique. The resulting assembly emulates a static linkage ofthe femur and tibia with the knee in flexion (e.g., at 30°, 60°, or 90°of flexion or increments there between) from which the surgeon canreference subsequent resection instruments as described below.

Also included in the assembly 10 is a quick connect locking mechanism 34that connects into the hex portion 19 of the central opening 18, asshown in FIGS. 8 and 9. Included in this embodiment of the lockingmechanism are a static outrigger arm 35, a spring-biased plunger 36 anda static clocking extension 37 which emulates the anti-rotation feature19, and in this instance has a hexagonal shape. The arm 35 has anelongate portion 38 and a rounded head portion 39. The elongate portion38 of the arm 35 has a square cross-section and extends from the roundedhead portion 39 which has a partially cylindrical shape with a pair ofopposing flats at its ends. Extending from one of the flats of therounded head portion is the hex extension 37. The hex extension 37 has ahexagonal cross-section configured to snugly fit within the hex portion19 of the central opening 18 defined in the femoral mount 15. As shownin FIG. 8, defined in one rounded surface of the head portion 39 is ahelically extending slot 43 which, as will be described below, guidesmotion of the plunger 36.

Defined through the rounded head portion 39 and the hex extension 37 isa cylindrical opening 40 through which the plunger 36 extends. Inparticular, the plunger 36 includes a thumb press 41, a shaft 42, aspring 45 and rotating extension 44 which emulates the anti-rotationfeature 37, in this instance is a hex, but could be any non-cylindricalshape, such as square, triangle or ellipse, capable of limitingrotation. The thumb press 41 is positioned at one end of the plunger 36and has the shape of a circular disk with ridges to promote pressingwith a thumb. Subjacent the thumb press 41 is the spring 45 which ispreferably in the shape of a coil and extends around the shaft 42 andbetween the thumb press and head portion 39 so as to bias them apart.

The shaft 42 includes a peg 46 that extends perpendicular to the shaftand into the helical slot 43 defined in the head portion 39, as shown inFIG. 8. Thus, depression of the thumb press 41 advances the shaft 42within the opening 40 in the head portion 39, and also results inrotation of the shaft as the peg 46 fixed thereto helically travels inthe helical slot 43. The hexagonal end 44 of the plunger 36 is fixed tothe end of the shaft 42 opposite the thumb press 41, extends along afree end of the hex extension 37 and has a hexagonal shape and sizematching that of the hex extension 37.

Due to its connection to the shaft 42, depression of the thumb press 41also causes rotation of the hexagonal end 44 of the plunger 36 until theflats of the hexagonal end match the orientation of the flats of the hexextension 37, as shown in FIG. 10. Matching of this orientation allowsinsertion of the hex extension 37 and the hexagonal end 44 into the hexportion 19 of the central opening 18 of the femoral mount 15, as shownin FIG. 11. Once the thumb press 41 is released, the spring 45 biasesthe thumb press, shaft 42 and hexagonal end 44 upwards, causing theflats of the hexagonal end to return to their non-matching, out-of-phaseposition (shown in FIG. 9) with respect to the flats of the hexagonalextension 37.

At this point, the hexagonal end 44 of the plunger 36 resides in thecylindrical portion 20 of the central opening 18 and, due to itsnon-matching position, cannot be withdrawn through the hex portion 19 ofthe central opening. As a result, the locking mechanism 34 becomesrotationally and translationally locked with respect to the femoralmount 15 and the femoral IM rod 13. Once locked in place, the arm 35 ofthe locking mechanism 34 extends anteriorly outward from the femoralmount 15 and the condyles of the femur 11. Notably, the combination ofthe relatively narrow femoral mount 15 and narrow, elongate structure ofthe arm 35 allows passage through relatively small surgical approachopenings, facilitating use of the assembly 10 with less invasiveprocedures. For example, a modified mid-vastus, medial mid-vastus orsub-vastus approach could be used with a small 8-10 cm cut which allowsavoidance of a release of the quadriceps from the anterior tibia.

Also included in the assembly 10 of the illustrated embodiment of theinvention is a flexion guide support member 47 which is supported by thelocking mechanism 34. Included in the flexion guide support member is aslider member 48 and a ratchet bar 49. The slider member defines arectangular opening 50 which is sized and shaped to allow the slidermember to be supported by, and slide along, the rectangularcross-section of the arm 35 of the locking mechanism 34. This motionallows the ratchet bar 49, which is attached to the slider member 48, tomove toward and away from the knee joint. The slider member 48 ispreferably shaped to have finger grips (e.g., the tapered portion of theillustrated slider member) and may also include some type of a pin orlocking assembly to resist, but not prohibit its sliding relative to thearm 35. The ratchet bar 49 itself is also rectangular shaped incross-section and, when assembled, extends distally from the arm 35 ofthe locking mechanism 34, as shown in FIG. 12. The ratchet bar 49 alsoincludes a pair of chamfered corners supporting a plurality of adjacentratchet grooves 51 extending along the length of the ratchet bar.

The assembly 10 also includes a flexed knee cutting guide assembly 52that attaches to the flexion guide support member 47, as shown in FIGS.13, 14 and 15. The flexed knee cutting guide assembly 52 includes aquick release mechanism 53 and a cutting guide 54. The quick releasemechanism 53 includes a body 55, a draw pin 56, first and second springs57, 58, a locking lever 59 and a locking pin 60. As shown in FIG. 16,the body 55 defines a rectangular opening 61 which allows the body to beslid over the rectangular cross-section of the ratchet bar 49. Inaddition, the body 55 includes a side opening into which the draw pin 56extends so that its end engages the ratchet grooves 51. In particular,the first spring 57 biases the draw pin into a position normallyengaging the ratchet grooves so as to lock the draw pin, and hence thebody 55, into a particular position on the slider member 48. The lockingpin 60 extends through the body and through the draw pin 56 to securethe draw pin 56 and prevent it from disassembly.

The body 55 additionally includes a clevis 62 that extends outwards fromthe opposite side of the body from the draw pin 56 and which supportsrotation of the locking lever 59 about its middle portion. As well shownin FIG. 17, the locking lever has a curved finger grip biased outwardfrom the body 55 by the second spring 58 and the opposite end of thelocking lever includes a tapered tongue 63 which, as will be describedbelow, engages the cutting guide 54 so as to lock the quick releasemechanism 53 thereto. Extending away from the clevis 62, opposite thelocking lever, is an engagement member 64 of the body 55. The engagementmember 64 has a rectangular cross-section and, in the assembledcondition shown in FIG. 13, extends into a connection with the cuttingguide 54.

As shown in FIG. 13, the cutting guide 54 extends posteriorly (whenassembled) from the quick release mechanism 53 and includes a mountingportion 65, a k-wire guide or fixation pin portion 66, a cross pinportion 71, a proximal tibial cut guide portion 67 and a posteriorcondylar femoral cut guide portion 68. The mounting portion 65 defines arectangular opening 69 that is sized and shaped to slidably receive theengagement member 64 of the body 55 of the quick release mechanism 53.The mounting portion 65 also defines a notch 70 in one of the sidewallsof the rectangular opening 69, as shown in FIG. 18. The notch 70 issized, shaped and positioned to receive the tapered tongue 63 of thelocking lever 59 when the locking lever is under the bias of the secondspring 58, as shown in FIG. 15. Release of the cutting guide 54 iseasily accomplished by depressing the free end of the locking lever 59,overcoming the bias of the second spring 58 and disengaging the taperedtongue from the notch 70 of the mounting portion 65.

The fixation pin (or k-wire) guide portion 66, the tibial cut guideportion 67 and the femoral cut guide portion 68 each have a crescentshape that extends in a medial-lateral direction around the anatomicalcurvature of the anterior-medial or anterior-lateral tibia (dependingupon which cut is being made), as shown in FIG. 13. The fixation pinguide portion 66 is adjacent the mounting portion 65 and defines aplurality of fixation pin holes 72 that extend in a posterior directionat an angle so as to guide fixation pins (used to fix the cutting guide54 before release of the other components of the assembly 10) into thethickest anterior portions of cortical bone on the tibia 12. Althoughless preferred, the number and orientation of the fixation pin holescould be varied depending upon the firmness of the connection desired,size and morphology of the tibia 12, etc.

The tibial cut guide portion 67 is positioned adjacent the fixation pinguide portion 66 and defines a slot for guiding the tibial cut. The slotextends along the length of the crescent shape of the guide portion 67and generally has a parallel orientation with respect to the tibialplateau. However, the resection plane defined by guide portion 67 mayvary in posterior slope (sagittal plane angularity) and varus/valgus(coronal plane angularity), depending on the desired position andpreference of the surgeon for the cutting guide 54. An example of such acut is illustrated in FIG. 19, wherein the tibia has a flat planar cutextending in the anterior-posterior and medial-lateral planes on theproximal end of the tibia 12. The femoral cut guide portion 68 isproximally spaced from the tibial cut guide portion 67 by a pair ofconnection flanges 73 so as to bridge the knee joint compartment.Similar to the tibial cut guide portion 67, the femoral cut guideportion 68 defines a slot that extends along the length of the crescentshape. However, because the knee is in flexion, the cut is guidedthrough the posterior of the condyles of the femur 11.

An advantage of the components of the assembly 10 for positioning cutswith the knee in flexion, including the femoral mount 15, the tibialmount 23, the flexion bolt 30, the locking mechanism 34, the flexionguide support member 47 and the flexed knee cutting guide assembly 52,is their usability with relatively non-invasive, narrow cuts in theanterior soft tissues of the knee (and with a retracted patella).Generally, as can be seen in FIGS. 14 and 15, the assembled componentsfor making the cuts in knee flexion are relatively narrow as they extendout of the joint space in a U-shape, while at the same time providing afirm connection for supporting the cutting guide 54, a quick assemblyand release of the components and accurate positioning of the flexedknee cutting guide. Considering the cutting guide 54 by itself (whichcan be positioned inside of the capsular incision), the width of thiscomponent is small compared to conventional cutting guides, for example,within a range of up to 4 to 5 cm thereby allowing their use withminimally invasive approaches to the knee joint.

The assembly 10 also includes instrumentation configured to guide cutswith the knee in extension (i.e., with the tibia and femur generallyaligned, or at 0° of flexion), as shown in FIGS. 19-29. For kneeextension, both the femoral IM rod 13 and the tibial IM rod 14 remain inplace, as shown in FIG. 19. However, instead of attachment of the tibialmount 23 to the tibial IM rod 14, a tibial angulation guide 74 isattached to the tibial IM rod. The tibial angulation guide 74 includes agauge block 76 and a post 97 which fits into an extension bolt 96(similar to the flexion bolt 30, but without the bushing 33). Theextension bolt 96 also has a hex flange 75. Alternatively, a separategauge block 76 may be employed with a shaft (as shown in FIG. 6) thatextends into an opening in the bushing 33, allowing removal of the bolt30 to be avoided.

Regardless, gauge block 76 extends upward from the plateau flange 28 ofthe tibial mount 23 when the threaded shaft of the extension bolt 96extends into the threaded opening 29 and defines an arc surface 77 and aplurality of gauge marks 78 defined on its anterior surface, as shown inFIGS. 19-21. The arc surface 77 is shaped and sized to receive the outersurface of the cylindrically shaped femoral mount 15 and allow thefemoral mount 15 to rotate in the varus-valgus direction and slide inthe anterior-posterior direction therein. These motions are left free soas to not over-constrain the femur 11 and tibia 12, but still promoteanterior-posterior alignment of the instruments and rotational positionselection, for better positioning of the tibial and femoral cuts. Othervariations and combinations of shapes of the femoral mount 15 and tibialangulation guide 74 could be employed to allow these ranges of motion,such as by reversing the shapes of the gauge block 76 (it having acylindrical shape) and the femoral mount 15 (it having the arc shape),by having a rounded shape between two plates, extending the angulationreadings away from the instrument assembly, etc., and still be withinthe purview of the present invention.

Adjustment of the relative proximal-distal positioning of the femur 11and the tibia 12 is accomplished, similar to the technique in theflexion position, by adjusting the rotation of the hex flange 75 of theextension bolt 96 with a torque wrench. This motion advances or retractsthe threaded shaft of the tibial extension bolt 96 into and out of thethreaded opening 29 in the tibial mount 23 and advances the tibialangulation guide 74 toward the femoral mount 15. Preferably, the femur11 and tibia 12 are distracted until the torque wrench has a readingsimilar to that for the knee in flexion to ensure that the joint is notoverly tight in knee extension. With respect to the torque wrench andthe amount of joint space, the torque wrench may be equipped with anextender that extends the length of the wrench, has hex-shaped jaws atits end and is relatively thin or low profile. If this is the case, thetorque measurements may be adjusted to compensate for the additionallength of the extender. In either case, the objective is to match thetorque value obtained when the instrument construct constrained the kneein some degree of flexion, in this instance 90° of flexion or incrementsthere between, and torque the bolt to a similar torque measurement thatwas reached on the torque wrench in the previous step, or until adequatetension of the ligamentous structure is obtained.

Referring again to FIGS. 20 and 21, the gauge marks 78 of the gaugeblock 76 radiate outward from the center of rotation of the femoralmount 15, starting at the outer surface of the femoral mount, and arepositioned on the anterior surface of the gauge block. The gauge marks78 of the gauge block 76 are configured to match up with gauge marks 21of the femoral mount 15 (as shown by the arrow) to indicate a valgusangle of the tibia 12 with respect to the femur 11. Generally, thevalgus angle should be within a range of 3 to 7 degrees, or even 2 to 9degrees, depending upon the knee's morphology, surgeon preference, etc.

Once the angulation and proximal-distal positioning of the tibia 12 withrespect to the femur 11 has been adjusted, an extension guide supportmember 79 is attached to the femoral mount 15 using a second lockingmechanism 84, as shown in FIGS. 22 and 23. Generally, the second lockingmechanism 84 includes the plunger 36 (and its components includinghexagonal end 44), hex extension 37 and helical slot 43 which aresimilarly numbered as they share a similar function with the samecomponents of the first locking mechanism 34. The second lockingmechanism 84 differs in that the head portion 39 is somewhat longer, iscylindrical and lacks the elongate portion 38 of the arm 35. Also, thesecond locking mechanism 84 includes a grip flange 86 positionedadjacent the plunger 36 to facilitate a finger grip when depressing theplunger. Regardless, the hexagonal end 44 has the same rotating motionthat facilitates quick attachment of the end of the second lockingmechanism 84 to the femoral mount 15.

The extension guide support member 79 includes a mounting portion 80, asupport arm 81 and a fixation flange 82. The mounting portion 80 has acylindrical shape with a cylindrical opening 83 extending there throughthat is configured to slidably receive the second locking mechanism 84,but is not rotationally constrained by said second locking mechanism 84.Extending away from one side of the mounting portion 80 is the supportarm 81 which is an elongate structure with a T-shaped cross section.Extending away from the other side of the mounting portion 80 is anadditional flange 82 that acts as a housing for a mechanism, in thiscase a ball and spring 85, to provide some resistance to rotation of theextension guide support member 79 with respect to the second lockingmechanism 84.

Also included in the illustrated embodiment of the assembly 10, is anextended knee cutting guide 87 that is supported by the extension guidesupport member 79 during positioning, as shown in FIGS. 24-29. Theextended knee cutting guide 87 includes a mounting portion 88, afixation pin (or k-wire) guide portion 89, a femoral cut guide portion90 and a reference lever 91. The mounting portion 88 is generallycentered in a body portion of the extended knee cutting guide 87 anddefines a channel 92 that has a cross-sectional shape matched to theT-shaped cross-section of the support arm 81. The matching shapes allowthe extended knee cutting guide 87 to slide in the proximal-distaldirection along the support arm 81.

The fixation pin guide portion 89 defines a plurality of k-wire (orother type of fastener, e.g., screws, nails, etc.) holes 93 that allowfixation using fixation pins after positioning of the extended kneecutting guide 87. The holes 93 are positioned on medial and lateralsides of the anterior femur when positioned so as to allow fixation torelatively thick cortical bone, as shown in FIG. 25. As with the k-wireholes 72, the k-wire holes 93 can be oriented at various angles orselectively positioned to guide fasteners into and through largerlengths of denser bone on the femur 11.

The femoral cut guide portion 90 extends either laterally or mediallyfor a uni-compartmental reconstruction (as with the illustratedembodiment), or in both directions for a full resection of the femoralcondyles. Notably, the guide portion 90 extends distally in the shape ofa U that fits around the second locking mechanism 84 when the extendedknee cutting guide 87 is in place, as well shown in FIG. 29. Regardless,the guide portion 90 extends distally from the k-wire guide portion 89and then laterally or medially to define a guide slot 94. The guide slot94 is of sufficient width to allow passage of cutting instruments orblades but still promote a relatively straight or planar resection.Notably, extension medially allows the laterally shifted patella to beavoided in a medially oriented approach to the knee joint compartment.

Extending further distally from the femoral cut guide portion 90 is aportion of the extended knee cutting guide 87 that defines a clevis 95that rotationally supports the reference lever 91. The reference leverextends laterally or medially and rotates in an anterior-posteriordirection to allow positioning in the joint compartment, as shown inFIGS. 24 and 25. The reference lever 91 has a broad, flat distal surfacethat is configured to rest against the flat tibial cut and a flatlateral surface is configured to abut the side surface of the plateauflange 28. These surfaces provide a stop for the distal movement of theextended knee cutting guide 87 along the support arm 81 of the extensionguide support member 79. With the reference lever 91 and the secondlocking mechanism 84 in place, fixation pins can be inserted through thepin holes 93 in the guide portion 89 to fix the femoral cut guideportion 90 to the femur 11. This allows removal of the extension guidesupport member 79, as shown in FIGS. 27, 28 and 29.

Advantageously, the components for positioning the cuts with the knee inextension, including the extension bolt 96, tibial angulation guide 74,the extension guide support member 79 and the extended knee cuttingguide 87 are configured for passage through an anterior and medialapproach to the knee compartment due to the narrow width and profile ofthe components. For example, as shown in FIG. 25, the posterior portionof the second locking mechanism 84 and the reference lever 91 would passthrough the incision and exhibit the aforementioned narrowness andlow-profile. Preferably, the width of this component is small comparedto conventional cutting guides, for example, within a range of up to 4to 5 cm thereby allowing their use with minimally invasive approaches tothe knee joint.

After these initial cuts, further cuts can then be made using theinitial cuts as a reference. As shown in FIGS. 30 and 31, an L-plate 99is employed to abut the posterior and distal flat surface of the femur11 to guide an anterior cut. Chamfer cuts (anterior and posterior) canbe made using a chamfer cut block and other finishing cuts can bereferences from the initial cuts made using the assembly 10 of thepresent invention. Additional description of these finishing cuts can befound in U.S. patent application Ser. No. 10/794,188 filed on Mar. 5,2004, entitled “Reference Mark Adjustment Mechanism for a FemoralCaliper and Method of Using the Same,” which is hereby incorporatedherein by reference.

In another embodiment of the present invention, as shown by FIGS. 32through 40, the assembly 10 includes additional modular options topromote quick assembly. As shown in FIG. 32, the femoral IM rod 13includes a secondary femoral mount 100. The secondary femoral mount 100has a saddle or crescent shape that extends laterally and distally froma central attachment to the distal end of the main shaft 16 of thefemoral IM rod 13. Defined in the inner, convexly curved surface of thesaddle is an opening 101 that is configured to receive a femoral mountrod 102 that supports the femoral mount 15, as shown in FIG. 33.

Referring again to FIG. 32, the tibial IM rod 14 includes a modifiedversion of tibial mount 23 supported by the shaft 22. In particular, theplateau flange 28 of the tibial mount 23 has a widened rectangular shapethat extends laterally outward from the threaded opening 29. Defined atthe anterior side of the plateau flange 28 are a pair of guide mountopenings 103 that extend posteriorly into the plateau flange. As shownin FIG. 34, the flexion bolt 30 may also be further modularized byproviding a post 104 for mounting the bushing 33 and hex flange 32within a central opening defined in a hex-head bolt 105 that includesthe threaded shaft 31 extending from its head 105. FIGS. 35 and 36 showthe assembly of the femoral mount 15 and tibial mount 32, along withtightening adjustment by elevation of the hex head bolt 105.

As shown in FIG. 37, the assembly 10 also includes a flexed knee cuttingguide assembly 52 that includes a flexed knee cutting guide 54 and adirect mount 106. The direct mount includes a pair of posts 107 that arespaced apart and extend from a mounting block 108. The spacing and sizeof the posts 107 are configured to extend into the guide mount openings103 defined in the plateau flange 28. Mounting block 108 can be coupledto tibial mount 32, such as by hermetically sealed magnets 111. Theflexed knee cutting guide 54 is attached to and extends distally fromthe mounting block 108. The flexed knee cutting guide defines aselection of slots 109 for guiding tibial and femoral cuts.

The posterior femoral cut can be accomplished by turning the flexed kneecutting guide assembly 52 upside down or by using another block whichwould be a modification of the upside down cutting guide assembly 52where the cutting guide 54 and selection of slots 109 is moved towardthe posts 107 and therefore, closer to the posterior femoral condyles ofthe knee. The selection of slots 109 of cutting guide assembly 52 can beas shown with the slots attached centrally or could be open centrallyand attached along both sides of the cutting guide 54.

As shown in FIGS. 38 and 39, the tibial IM rod 14 may also include avalgus adapter member 110 or a modified version of femoral mount 15 thathas its own post that is configured to insert into the central openingof the hex head bolt 105. As shown in FIG. 40, the valgus adapter member110 has a convex shape that is configured to extend into the concaveshape of the secondary femoral mount 100. This mating allowsvarus-valgus angulation to position the cuts when the knee is inextension, similar to the first embodiment disclosed above. Extendedknee cutting guides can be mounted similar to the flexed knee cuttingguide via posts 107.

The assembly 10 of the present invention has many advantages. Itprovides a relatively narrow and low profile collection of lockingcomponents that securely attach cutting guides to tibial and/or femoralIM rods. This provides a robust guide to reference cuts being made tothe tibia and the femur with an approach to the joint that minimizesinvasiveness. Further, many of the components, such as the first andsecond locking mechanisms 34, 84 and the quick release mechanism 53,facilitate quick assembly, easy adjustment and quick disassembly forimproved efficiency. The use of the bolts 30 and 96 or 105 and thetibial angulation guide 74 or valgus adapter member 110 allow the tibiaand femur to be distracted under a matching amount of torque in flexionand extension to ensure a better fit for the tibial and femoral kneereplacement components throughout a range of flexion. Also, the tibialangulation guide allows the surgeon to adjust the amount of valgusangulation of the tibia as desired to match the anatomy of the patient.

As shown in FIG. 41, in another embodiment of the present invention amodified femoral mount rod 102 and femoral mount 15 with a hingemechanism attaching mount 15 to the femoral mount rod 102 could be usedwith a retractor rod placed thru the hole 18 in the femoral mount 15 andguided posterior to the tibia thus providing a fulcrum and lever arm forthe retractor to displace the tibia forward or anterior to allowexposure for placement of the tibial component of the total kneearthroplasty after the bone cuts have been made. Since the IM rods fixrigidly to the bone, other retractors could also be attached to theGuide Assembly to facilitate knee exposure during the knee surgery.

As shown in FIG. 42A, in another embodiment of the present inventionmini-trial components or trial components which are smaller but shapedwith identical (or substantially identical) thickness and radii to theactual knee arthroplasty implants, designed to fit in holes 101 offemoral IM rod 13 and 29 of tibial IM rod 14 and articulate in thecenter portion of the knee could be used to check alignment and ligamentstability prior to placement of the actual final knee arthroplastyimplants. This design of a centrally placed mini-knee arthroplastyimplant system could become a stand-alone total knee arthroplasty. Oneadvantage of this embodiment of the present invention is that thesmaller instruments take up less space. The mini-trial femoral componentcould be designed with cutting surfaces or slots for making the chamfercuts and other finishing cuts, thus eliminating the need for a chamfercut block and L-plate 99 shown in FIGS. 30 and 31.

Additionally, while such trial components can comprise any suitablecomponent or characteristic, FIGS. 42B-42E show that in someembodiments, the trail femoral implant 600 comprises a convex roundedsurface that is configured to articulate against a concave or recessedsurface of the trial tibial component 602. Additionally, in someembodiments, one or more components of the trial tibial component andthe trial femoral component are selectively adjustable via any suitableadjustment mechanism to change a gap between the femur and tibia (e.g.,distally, posteriorly, and/or otherwise).

Moreover, such trial components (centrally placed gap balancers and/orspacers) can be used with any other suitable component described herein,including, without limitation, with the spacers 500 discussed below.

Referring now to FIGS. 43-48, another embodiment of the presentinvention is shown. Specifically, FIGS. 43-45 illustrate animplementation of the current invention for resecting a patient's kneein flexion, and FIGS. 46-48 illustrate an implementation of the currentinvention for resecting a patient's knee in extension. The femoral mount150 of the femoral IM rod 113 of each embodiment comprises a planarflange that is substantially inset, and flush with the insertion site ofthe femur 11. In one embodiment, a rongeur is used to prepare the distalfemur for a ⅜ inch drill entry. Following insertion of the drill, aplanar is then used to clear the remaining bone from the insertion siteand to provide a recessed surface into which the femoral mount 150 isseated. A threaded opening 129 extends into the femoral mount 150 andprovides a coupling attachment for an extension bolt 130, which includesa threaded shaft 131, a circular flange 132 with mounting holes 133, anda centralizing ball 134, as shown in FIGS. 46 and 47. Additionally, thethreaded opening 129 provides a mounting channel into which anon-threaded post 114 of a threaded barrel 115 is inserted. Theinteraction between the non-threaded post 114 and the threaded opening129 sufficiently retains the threaded barrel 115 within the femoral IMrod 113 and permits axial rotation of the threaded barrel 115 relativeto the IM rod 113. Axial rotation is desirable to permit limitedmovement of the surgical tool relative to the natural physiology of thepatient's knee. As such, the threaded barrel 115 is permitted to rotateand facilitate the natural alignment of the patient's knee throughoutthe tensioning process, as described below.

The threaded barrel 115 comprises a non-threaded post 114perpendicularly coupled to an outer surface of a threaded opening 116.The threaded opening 116 extends through the threaded barrel 15 andprovides a coupling attachment for a flexion bolt 120. The flexion bolt120 includes a threaded shaft 121, a circular flange 122 with mountingholes 123, and a non-threaded tip 124. The threaded shaft 121 compatiblythreads through the threaded opening 116 such that the non-threaded tip124 exits and extends beyond the threaded barrel 115. The circularflange 122 is perpendicularly attached to the threaded shaft 121opposite the non-threaded tip 124. The flange 122 is circular andgenerally disk-shaped having a plurality of mounting holes 123 evenlyspaced around the circumferential edge of the flange 122. The mountingholes 123 are sized and configured to compatibly receive a torque wrench140 or other device for turning the flexion bolt 120. In accordance withsome embodiments (e.g., as illustrated in FIGS. 43 and 44, the describeddevice allows for changes in varus-valgus angulation of the knee jointwhen the tibia and femur are tensioned with respect to each other whenthe knee is in flexion.

The current embodiment further comprises a tibial tensioning adapter160. The tibial tensioning adapter 160 is stably supported by the tibialIM rod 170 and positioned generally perpendicular to the main shaft ofthe tibial IM rod 170. The tibial tensioning adapter 160 comprises abase member 161 and a resection block guide 165. The base member 161 isgenerally planar and disc-like, having a centrally located opening 162that extends into the main shaft of the tibial IM rod 170. A bushing 125is further provided to compatibly seat within the opening 162. Thebushing 125 comprises a post portion 126 having a first diameter, and asleeve portion 127 having a second diameter and an opening 128. Thediameter of the post portion 126 is selected to compatibly insert withinthe opening 162 of the base member 161, while the diameter of the sleeveportion 127 is selected to be greater than the diameter of the opening162. As such, the sleeve portion 127 rests on the upper surface of thebase member 161 and is prevented from inserting into the opening 162.The opening 128 of the sleeve portion 127 is non-threaded and sized tocompatibly receive the non-threaded tip portion 124 of the flexion bolt120. Additionally, the interaction between the post 126 and the opening162 does not utilize threads thereby allowing the bushing 125 to freelyrotate within the opening 162 of the tibial tensioning adapter 160, andallowing the non-threaded tip 124 of the flexion bolt 120 to freelyrotate within the opening 128 of the bushing 125. These freely rotatinginteractions prevent rigid structuring or position of the surgical toolsthereby further permitting the natural physiology of the patient's kneeto be maintained during the tensioning and resection processes. Thus,the flexion bolt 120, the threaded barrel 115, and the bushing 125 arecombined with the femoral mount 150 and the tibial tensioning adapter160 to apply tension to the patient's knee preparatory to performing thedesired resections.

The base 161 further comprises a pair of spacers 163 forming a portionof the base member upper surface. The spacers 163 are generally pyramidshape and linearly configured on opposing sides of the opening 162. Thespacers 163 are provided to create a gap between the circular flange 132of the extension bolt 130 and the upper surface of the base member 161,as shown in FIG. 47. The pyramidal shape of the spacers 163 permitslimited radial movement of the extension bolt 130 relative to the basemember 161. This limited movement is desirable to accommodate thenatural physiology of the patient's knee throughout the tensioningprocess, described below in connection with FIGS. 46 and 48.

The resection block guide 165 is fixedly coupled to an edge surface ofthe base member 161 and extends outwardly therefrom. The block guide 165is generally aligned with the spacers 163 and positioned to extendoutwardly from the anterior surface of the knee. The block guide 165further comprises a plurality of notches 166 occupying an upper surfaceof the guide 165. The notches 166 span a portion of the upper surfaceand provide a coupling attachment for a resection block 180, as shown inFIGS. 45 and 48. The notches 166 further provide a plurality ofreference points or positions by which to gauge the position of theresection block 180.

Referring now to FIG. 44, an embodiment of the assembled invention isshown. Once the surgical device is assembled, a torque wrench 140 isinserted into a hole 123 of the circular flange 122 and the flexion bolt120 is rotated. Alternatively, in one embodiment the flexion bolt 120 isinitially rotated by hand until the femur 11 begins to lift away fromthe tibia 12. The torque wrench 140 is then utilized to further rotatethe flexion bolt 120 to a desired tension. This will typically result ina final tension of about 10-20 in/lbs. The amount of tension will differfor each patient based on individual physiology, injury, and ligamentviscoelasticity of the knee. Once the final tension in flexion has beenattained, the final amount of tension placed on the ligaments in isrecorded for future reference.

Referring now to FIG. 44A, an embodiment of the assembled invention isshown. In this embodiment, the flexion bolt 120 is substituted with aratcheting device 142. The ratcheting device 142 generally comprises ahandle portion 143, a biasing portion 144, and a gear box 145. Thebiasing portion 144 of the ratcheting device 142 is interposed betweenthe threaded barrel 115 and the bushing 125. The handle portion 143 isthen actuated to cause the biasing portion 144 to lift the femur 11 awayfrom the tibia 12. The gear box 145 converts the motion, or actuation ofthe handle portion 143 to change the position of the biasing portion 144and separate the knee joint.

The handle portion 143 may include any configuration whereby a physicianmay manipulate the handle portion 143 to actuate the biasing portion 144of the device 142. For example, in one embodiment the handle portion 143comprises a pair of opposing levers 146 and 147, each having a grip 148at a distal end and extending into the gear box 145 at a proximal end.The biasing portion 144 of the device 142 is actuated by gripping thehandle portion 143 and squeezing, such that the pair of opposing levers146 and 147 is brought to a proximal position. The action of theopposing levers 146 and 147 manipulates the gear box 145 causing thebiasing portion 144 to move away from a proximal position. Additionally,in one embodiment the gear box 145 includes a release for returning thebiasing portion 144 to a proximal position.

In another embodiment, the handle portion 143 comprises a single shafthaving a handle at the distal end, and extending into the gear box 145at the proximal end. In this embodiment, the biasing portion 144 of thedevice 142 is actuated by rotating the handle portion 143 in a clockwiseor counter-clockwise direction. The rotating action of the handleportion 143 manipulates the gear box 145 causing the biasing portion 144to move away from, or towards a proximal position. In one embodiment,the gear box 145 further includes a pawl or other device for maintainingthe biased position of the biasing portion 144 during use. As such, aphysician may actuate the device 142 to separate the knee to a desiredposition or tension, and then maintain the tension hands-free.

The biasing portion 143 may include any configuration capable ofmounting into the threaded barrel 115 and the bushing 125. For example,in one embodiment the biasing portion 143 includes a pair of jaws 148having a first end for engaging the threaded barrel 115 and the bushing125, and having a second end extending into the gear box 145. In anotherembodiment, the first end further includes a jointed connector 149 forengaging the threaded barrel 115 and the bushing 125. The jointedconnector 149 permits the pair of jaws 148 to separate the knee joint,yet provide limited movement of the knee joint to accommodate thenatural physiology of the patient's knee throughout the tensioningprocess.

The gear box 145 may include any configuration of gears compatible withthe handle portion 143 and the biasing portion 144 to achieve controlledseparation of the knee joint. The gear box 145 may also include anymeans for limiting or measuring the tension placed on the knee joint.For example, in one embodiment the gear box 145 further comprises atension meter 151 whereby the tension placed on the knee joint, by theratcheting device, 142 is displayed. In another embodiment, the gear box145 further comprises an adjusting screw 152 whereby the maximum allowedtension of the ratcheting device 142 is set. In this embodiment, aphysician adjusts the adjusting screw 152 to a desired tension. Onceset, the physician actuates the ratcheting device 142 to separate theknee joint. When the desired tension is achieved, further tensioning byactuation of the ratcheting device 142 is prevented, thus maintainingthe desired tension for the knee. While the apparatus shown in FIG. 44Acan perform any suitable function, in some embodiments, FIG. 44A showsthat the ratcheting device 142 (and/or any other suitable device) allowsfor changes in the varus-valgus angulation between the tibia 12 and thefemur 11 to occur when the two bones are in tension with respect to eachother (e.g., when the knee joint is in flexion and/or extension).

Referring now to FIG. 45, the resection block 180 is attached to theresection block guide 165 and slid into position against the anteriorsurface of the femur 11. The resection block 180 is secured to theresection block guide 165 by tightening a set screw 183 against thenotches 166 of the guide 165. The resection block 180 is then secured tothe femur 11 via a plurality of screws 181. Once the resection block 180is secured in position, the flexion bolt 120 is removed from thesurgical tool assembly and the cutting guides 182 of the resection block180 are used to resect the exposed distal surfaces of the lateral andmedial condyles.

Referring now to FIGS. 46-48, an implementation of the current inventionis provided for operation in knee extension. Referring to FIG. 46, theextension bolt 130 is shown prior to being interposed between thefemoral mount 150 and the tibial tensioning adapter 160. The extensionbolt 130 generally comprises a threaded shaft 131, a circular flange 132and a centralizing ball 134. The threaded shaft 131 is configured tocompatibly thread within the threaded opening 129 of the femoral mount150. The circular flange 132 is perpendicularly attached to the threadedshaft 131 and interposed between the threaded shaft 131 and thecentralizing ball 134. The flange 132 is disk shaped having a pluralityof mounting holes 133 evenly space around the circumferential edge ofthe flange 132. The mounting holes 133 are sized and configured tocompatibly receive a torque wrench 140 or other device for turning theextension bolt 130.

The centralizing ball 134 comprises a hemispherically shaped surfacethat is sized and configured to partially insert within opening 162 ofthe tibial tensioning adapter 160. As such, the centralizing ball 134partially engages the opening 162 yet remains sufficiently free toprovide axial rotation between the femur 11 and the tibia 12. Theinterface between the centralizing ball 134 and the opening 162 furtherensures accurate alignment of the femoral mount 150 with the tibialtensioning adapter 160. Radial rotation is further provided to the femur11 and the tibia 12 due to the interface 158 between the circular flange132 and the spacers 163, as previously discussed and as shown in FIG.47. Thus, the extension bolt 130 provides both alignment and limitedfree adjustment to the femur 11 and tibia 12 during the tensioning andresection procedures.

In one embodiment, the extension bolt 130 is first coupled to thefemoral mount 150 by threading the threaded shaft 131 into the threadedopening 129 of the femoral mount 150, with the knee in flexion, as shownin FIG. 46. The extension bolt 130 is maximally inserted into thethreaded opening 129 to minimize the distance between the femur 11 andthe tibia 12. The knee is then brought into extension and thecentralizing ball 134 is inserted into opening 162, as shown in FIG. 47.A torque wrench 140 is then utilized to rotate the extension bolt 130and apply tension the knee. The torque wrench 140 is inserted into ahole 133 of the circular flange 132 and turned to gradually remove theextension bolt 130 from the threaded opening 129. In one embodiment, thephysician immobilizes the resection block guide 165 to prevent rotationof the tibia 12 during rotation of the extension bolt 130. The physiciancontinues to turn the extension bolt 130 until the desired tension isplaced on the ligaments of the knee. Alternatively, a ratcheting device(see FIG. 44A) may be used with the knee in extension to place thedesired tension on the ligaments of the knee. In one embodiment, thefinal tension in extension is equal to the final tension in flexion. Inanother embodiment, the final tension in extension is different than thefinal tension in flexion.

As illustrated in FIGS. 46 and 47, some embodiments of the describedsystems are configured to allow the femur 11 and tibia 12 of a kneejoint to rotate with respect to each other in order to change avarus-valgus angulation of the knee joint when the knee joint is undertension. Thus, in some embodiments, the described systems allow forproper tension, gap balancing, and varus-valgus angulation to beachieved relatively easily and quickly during full or partial kneereplacement.

Referring now to FIG. 48, the resection block 180 is attached to theresection block guide 165 and slid into position against the anteriorsurface of the femur 11, as discussed above in connection with FIG. 45.Once positioned, the resection block 180 is secured to the femur 11 withscrews 181 and the anterior surfaces of the lateral and medial condylesare resectioned.

In another embodiment, since the guide assembly is fixed rigidly to thebone and left in place during the essential steps of the kneepreparation, computer assisted guides are attached to the guide assemblyinstruments thus facilitating computer assisted total knee replacement.In other embodiments of the present invention, the guide assemblyinstruments are modified for use in a partial or uni-compartmental kneearthroplasty procedure.

In some embodiments, the Guide Assembly Instruments can be modified foruse with short IM rods or a tibial platform instead of an IM rod forextramedullary knee preparation.

In some embodiments, the Guide Assembly holds a patient's leg in place.This decreases the need for medical assistants to hold the patient'sleg.

Following a completed resection of the patient's knee joint, theresectioned portions of the femur 11 and the tibia 12 are replaced by aknee prosthesis or implant 200, such as shown in FIGS. 49 and 50. Theknee implant 200 generally comprises a femoral component 202 and atibial component 204. Although the instruments of the invention can beused with any type of knee prosthesis 200, the instruments areparticularly well-suited for use in accurately resecting the knee forreceipt of a knee prosthesis that employs a constant radius throughoutthe primary range of flexion, such as Wright Medical Technology, Inc.'sADVANCE® medial pivot knee implant. The features and characteristics ofconstant radius knee prostheses are well known to those of skill in theart, but have not previously been used with knee tensioning resectioninstruments. As will be described below, a synergistic and previouslyunappreciated effect is obtained by using the tensioning instruments incombination with prior art constant radius knee implants. It isanticipated that the end result of this synergistic combination will begreater overall accuracy in the implantation of constant radius kneeimplants, with resulting improvements in clinical outcomes.

One of the benefits of a properly designed and implanted constant radiusknee prosthesis is that it provides the patient with constant ligamenttension throughout the primary range of flexion. As discussed herein,the use of the instruments of the invention to resect the knee whileunder optimum tension helps insure accurate placement of the kneeimplant components. The combined use of tensioning instruments andconstant radius knee implants improves the likelihood of achievingconstant ligament tension throughout the primary range of flexion.Various embodiments of knee implants that incorporate a constant radiusare discussed in the following prior art documents, which areincorporated herein by reference: U.S. Pat. No. 7,261,740; U.S. Pat. No.6,013,103; U.S. Pat. No. 6,013,103; U.S. Pat. No. 5,824,100; U.S. Pat.No. 5,330,533; U.S. Pat. No. 5,326,361; U.S. Pat. No. 5,314,482; U.S.Pat. No. 5,219,362; U.S. Pat. No. 5,133,758; U.S. Pat. No. 4,085,466;German Patent Application 3314038A1.

In the prior art ADVANCE® Medial Pivot knee implant, the femoralcomponent 202 has a spherical condyle 206 on the medial side. Asindicated in FIG. 51, in the sagittal or A-P plane, the medial femoralcondyle 206 has a constant radius 226 over at least the primary range offlexion, which extends from about 0 degrees in extension to about 90degrees in flexion, depending on the patient. The lateral femoralcondyle 222 also has an A-P constant radius 226 throughout the primaryrange of flexion. The medial side of the tibial base 204 of the ADVANCE®Medial Pivot knee has a shallow spherically concave bearing surface 232,which is sized to closely receive the medial femoral condyle 206 in aball-and-socket manner. The lateral side of the tibial base 204 isgenerally in the form of an elongated arcuate trough 230. These featuresallow the medial femoral condyle 206 to pivot in the medial tibialbearing 232 during flexion, while simultaneously permitting the lateralfemoral condyle 222 to translate posteriorly in the lateral tibialbearing 218. This action is designed to mimic the function of thenatural knee, in which the medial femoral condyle exhibits less rollbackthan the lateral condyle during motion. Features and characteristics ofthe ADVANCE® Medial Pivot knee are discussed in greater detail in U.S.Pat. Nos. 5,964,808 and 6,013,103, which are incorporated herein byreference. Although the ADVANCE® Medial Pivot knee implant is anexemplary implant design for optimizing and complementing the use of thetensioning instruments of the invention, other constant radius kneeimplant designs can be used to similar or equal effect.

One of the drawbacks of prior art knee instruments is that overstuffingor under filling the joint sometimes occurs, with resulting tightness orlaxity, respectively, in the ligaments. As discussed above, use of thetensioning instruments to resect with the knee tensed in the extendedposition allows the user to make a balanced extension gap resection whencompared with the tensed resections made with the knee previouslypositioned in flexion. The resection cuts are made off of a singlereference point, the single reference point being the desired amount oftension. The use of equal flexion and extension gaps automaticallybalances the mid-flexion gap at all points in between. By thenimplanting a constant radius knee implant onto the resectioned knee, thesurgeon effectively transfers the optimum tension obtained by thetensioning instruments to the constant radius knee implant, resulting ina stable, smoothly functioning knee throughout at least the primaryrange of flexion. In mechanical terms, the tensioning technique preloadsthe bearing, the bearing being the constant radius knee implant.

In contrast, if a conventional J-curve or varying radius knee implant isused with the tensioning technique, rather than a constant radiusimplant, it becomes necessary to vary the cuts instead of using an equalflexion and extension gap. The use of a varying radius knee implant thusnecessarily complicates the process and the use of the instruments.

In addition to the aforementioned components and characteristics of thedescribed systems and methods, in some embodiments, the describedsystems and methods are configured to be used with one or more robots,robotic arms, laparoscopic devices, and/or other automated devices.Indeed, in accordance with some embodiments, the described systems andmethods are used to provide a desired tension to a knee joint and anautomated device (e.g., the MAKO™ robotic arm produced by Stryker ofKalamazoo, Mich. USA and/or any other suitable robotic and/or automatedassembly) is then used to resect one or more portions of bone in theknee joint. In such embodiments, the automated device can make the cutsin any suitable manner. Indeed, in some embodiments, the automateddevice uses one or more cutting guides 54, femoral cut guide portions90, flexed knee cutting guide assemblies 52, and/or any other suitablecomponents that are configured to direct a cutting tool. In some otherembodiments, however, the automated device is configured to make desiredcuts in the knee joint without the use of the described cutting guidesor guide/resection blocks.

As another example of a suitable modification, some embodiments of thedescribed apparatuses and systems are configured to maintain tension inone or more ligaments of the knee joint throughout a range of motion ofthe joint. In this regard, in some embodiments, one or more componentsof the described systems and methods are changed between adjustingtension in the knee joint in flexion (e.g., as shown in FIGS. 7-15,33-37, and 43-45) and in extension (e.g., as shown in FIGS. 9-19, 38-40,and 46-48).

In some other embodiments, however, the described systems and methodscomprise one or more articulated connectors that comprise part of and/orthat extend between a femoral component (e.g., the femoral IM rod 13,the femoral mount 15, the secondary femoral mount 100, the opening 129in the femoral mount, and/or any other suitable femoral component), atibial component (e.g., the tibial IM rod 14, the tibial mount 23, theplateau flange 28, the tibial tensioning adapter 160, the hole 162 inthe tensioning adapter, and/or any other suitable tibial component), thetensioning assembly (e.g., the flexion bolt 30, the extension bolt 96,the gauge block 76, the bushing 33, the valgus adapter member 110, theflexion bolt 120, the threaded barrel 115, the bushing 125, theratcheting device 142, the extension bolt 130, and/or any other suitablecomponent that is used to increase and/or decrease tension in a kneejoint), and/or any other suitable component of the described systems andmethods).

By way of non-limiting illustration FIG. 52A shows that, in someembodiments, the femoral IM rod 13 is configured to comprise a joint 156that allows the femoral mount 15 to pivot so that a knee jointcomprising such a rod can be moved through a range of motion withoutrequiring different components to be used in extension and flexion. Inanother non-limiting illustration, FIG. 52B shows that, in someembodiments, the guide block 76 comprises a joint 156 that allows it topivot so that a knee joint comprising such a block and a femoral mount15 (e.g., as shown in FIG. 1) can be moved through a range of motionwithout requiring different components to be used in extension andflexion. In still another non-limiting illustration, FIG. 52C shows anembodiment in which the extension bolt 130 comprises a joint 156 thatallows the bolt to pivot so that a knee joint comprising such a bolt andthe tibial tensioning adapter 160 can be moved through a range of motionwithout requiring different components to be used in extension andflexion (e.g., an extension bolt and a flexion bolt).

Where the described systems and methods comprise one or more articulatedconnectors, the connectors can have any suitable component orcharacteristic. By way of example, the articulated connectors cancomprise any suitable type of joint, including, without limitation, oneor more pivot joints, ball joints, hinge joints, universal joints,prismatic joints, rotoide joints, and/or other suitable joints thatallow the knee joint to move through a range of motion when suchconnectors are disposed in the joint and coupled to one or morecomponents of the described apparatuses and systems. As another example,some embodiments of the articulated connectors comprise one or morestops (e.g., ridges, rings, protuberances, and/or other stops 159) thatare configured to retain a sufficient amount of the connectors outsideof the femur and/or tibia to allow a portion of each connector (andhence the knee joint comprising the connector) to move through a rangeof motion without undesirable impingement on another object (e.g., bone,a femoral component, a tibial component, etc.). In still anotherexample, some embodiments of the articulated connectors comprise one ormore detents, locks, locking mechanisms, limits, clamping mechanisms,and/or other position retaining mechanisms that allow the connectors tobe selectively moved from and/or be retained in desired positions.

Bone Milling

With reference now to the described bone milling technology, someembodiments of the present invention relate to the use of instrumentsfor guiding preparation of a knee for resection, as well as for guidingpreparation of a knee for installation of an implant during anarthroplasty. In particular, some embodiments relate to a system forguiding a milling tool along a specific axis to provide an aperture of adesired depth.

Referring now to FIG. 53, a perspective view of an implementation of thecurrent invention is shown as positioned within a knee 312 in flexion,shown in phantom. The bone milling device 310 comprises a milling bit320 and a guide rod 340. The bone milling device 310 generally comprisessurgical metal materials that are compatible with surgical applications,such as surgical steel, titanium, aluminum, and alloys thereof. However,one of skill in the art will appreciate that other non-metallicmaterials, such as Teflon and nylon, may be incorporated into thecurrent invention within the scope of the present disclosure. Forexample, in one embodiment a Teflon coating is applied to opposingsurfaces of the bone milling device 310 to reduce friction.

Referring now to FIGS. 53-55, the milling bit 320 comprises a cuttinghead portion 322 and a shaft portion 324. The cutting head portion 322is generally bell-shaped having a wider base 326 and a narrower, taperedtop 328 that joins the shaft portion 324. In some implementations of thecurrent invention, a ledge or stepped surface 330 is interposed betweenthe cutting head portion 322 and the shaft portion 324 to support adepth gauge 360, as shown in FIG. 55. The shaft portion 324 furthercomprises a shank 366 for coupling the milling bit 320 to a drill orother device for rotating the bit 320.

The cutting head portion 322 further comprises a removable blade 332.The removable blade 332 is generally disk shaped having a cutting edge334 and a window 336. The cutting edge 334 is provided to cut throughthe bone to create the aperture 350, while the window 336 is provided toremove the cut bone debris from the aperture 350. In this manner, theaperture 350 is both cut and cleared by the milling bit 320. The cuttinghead portion 322 further includes a window 338 that aligns with thewindow 336 of the removable blade 332. As such, bone debris is entirelyremoved from the cutting head portion 322 of the milling bit 320 anddoes not interfere with the ability of the milling bit 320 to form theaperture 350.

The milling bit 320 further comprises a cavity 352 extending through thecentral core of the shaft portion 324 and the cutting head portion 322.The cavity 352 is closed on one end and includes an opening 354 in thecutting head portion 322 of the bit 320. The cavity 352 comprises adiameter that is adapted to rotatably receive a portion of the guide rod340. The tolerance between the cavity 352 and the guide rod 340 permitsthe bit 320 to freely rotate around the guide rod 340 yet controls andlimits the movement of the bit 320 relative to the axis of the guide rod340. As such, the interaction between the cavity 352 and the guide rod340 ensures that the angle of the aperture 350 is parallel to the angleof the guide rod 340.

The guide rod 340 is inserted or anchored within a portion of the bone314 that is to receive the aperture 350. Typically, the bone 314 ispredrilled to provide an access or opening 346 into the intramedullary(IM) canal 348 of the bone. The pre-drilling procedure is common to thearea of orthopedic medicine. Following this procedure, a first end 344of the guide rod 340 is inserted into the opening 346 and positionedwithin the IM canal 348 such that a portion of the second end 342 of theguide rod 340 extends outwardly from the opening 346.

In one embodiment, the first and second ends 344 and 342 of the guiderod 340 are threadedly coupled to form the guide rod 340. As such, thefirst end 344 of the guide rod 340 may threadedly receive a plurality ofcompatible surgical devices. For example, in one embodiment the secondend 342 of the guide rod 340 is removed, following creation of theaperture 350, and replaced with another surgical instrument needed tocomplete the arthroplasty procedure.

The second half 342 of the guide rod 340 comprises a post portion 356and a base 358. The base 358 is threadedly coupled to the first end 344and generally comprises the same diameter as the first end 344. The postportion 356 extends outwardly from the base 358 and is substantiallypositioned exterior to the IM canal 348. As previously discussed, thediameter of the post portion 356 is selected and adapted to rotatablyinsert within the cavity 352 of the milling bit 320. In one embodimentthe diameter of the base 358 is made greater than the diameter of thepost portion 356 so as to increase the surface area of the guide rod 340in contact with the IM canal, yet still provide the post portion 356with a diameter compatible with the cavity 352. In another embodiment,the base 358 and the first end 344 further include fluted outer surfacesto enhance contact with the IM canal 348 and prevent rotation of theguide rod 340 within the IM canal 348.

The depth and positioning of the guide rod 340 within the IM canal isselected to permit the milling bit 320 to precisely cut the aperture 350to a desired depth. The accuracy of the depth of the aperture 350 is acrucial element of any arthroplasty procedure. As such, the millingdevice 310 further comprises means for accurately determining the depthof the aperture 350. For example, in one embodiment the outer surface ofthe shaft portion 324 comprises a plurality of annular reference marks368. The reference marks 368 provide a visual indication of the depth ofthe removable blade 332 relative to various physiological references onthe bone being cut. In an embodiment where the aperture 350 is being cutinto the tibia 314, the required depth of the aperture 350 is either 2mm below the normal level 370 of the bone, 13 mm below the tibial spines372, or 10 mm below the lateral side 374. Thus, the reference marks 368are observed relative to the physiological references 370, 372 and 374to determine the depth of the aperture 350. Where the aperture is beingcut into another bone, such as the femur 316, other boney references areused, as known in the art.

In another embodiment, a depth gauge 360 is placed over the shaftportion 324 of the bit 320 and supported by the stepped surface 330. Thedepth gauge 360 includes a base 362, an arm 364 and a pin 366. The base362 further includes an aperture having a diameter to rotatably receivethe shaft portion 324 of the bit 320. The arm 364 extends outwardly fromthe base 362 so as to position the pin 366 beyond the aperture 350. Inone embodiment, the arm 364 further comprises a joint to adjust thelength of the arm 364. In another embodiment, the arm 364 furthercomprises a set screw to adjust and lock the pin 366 to a desiredposition relative to the arm 364. In yet another embodiment, a pluralityof depth gauges 360 is provided to accommodate various physiologicalreferences on the bone being cut.

The depth gauge 360 provides a physical indication of the depth of theremovable blade 332 relative to the various physiological references, aspreviously discussed. In one embodiment, the depth gauge 360 is seatedagainst the stepped surface 330 and the arm 364 and the pin 366 areadjusted to be in alignment with the desired physiological reference374. Additionally, the height of the pin 366 is set relative to thephysiological reference to produce an aperture 350 of a desired depth.Thereafter, the depth gauge 360 is held in place and prevented fromrotating while the bit 320 is rotated to form the aperture 350. Once thepin 366 touches the physiological reference 374, the bit 320 is removedfrom the aperture 350, having achieved the desired depth.

Referring now to FIG. 56, another method for accurately cutting theaperture 350 to a desired depth is shown. In this method, the desiredaperture 350 depth is attained by cutting into the bone 314 until thecutting bit 320 contacts the base 358 of the guide rod 340. This methodrequires that the base 358 of the guide rod 340 be accurately positionedwithin the IM canal 348 relative to the cutting edge 334 of the blade332. Therefore, the blade 332 cuts and descends into the bone 314 alongthe guide rod 340 until the point at which the cutting head 322 contactsthe base 358. Once contact between the cutting head 322 and the base 358occurs the milling bit 320 is removed from the aperture 350. In oneembodiment, the cutting head portion 322 of the milling bit comprises arecessed compartment 380 having a diameter adapted to compatibly androtatably receive the base 358 of the post portion 356. Thus, in thisembodiment the depth of the base 358 is set within the IM canal 348 suchthat when the base 358 fully engages the recessed compartment 380, thecutting edge 334 of the blade 332 is positioned accurately at thedesired depth of the aperture 350. While several different methods havebeen discussed, one of skill in the art will appreciate that variousother methods and apparatuses may be successfully combined with themilling device 310 to achieve the desired results.

Referring now to FIG. 57, the tibia 314 is shown following formation ofthe aperture 350 and prior to resection. Once the aperture 350 isprovided, the guide rod 340 may be further utilized to assist incompleting the arthroplasty procedure. For example, in one embodiment aresection block 390 is positioned over the guide rod 340, via a channel402, and seated within the aperture 350. The resection block 390comprises a base 392, an arm 394, and a cutting guide block 396. Thebase further comprises a flange portion 400 having a diameter equal tothe diameter of the aperture 350. Additionally, the base 392 includes achannel 402 having contours and dimensions adapted to compatibly engagethe post portion 356 and the base 358 of the guide rod 340. As such, theresection block 390 accurately seats within the aperture 350 and issteadied by the interposing and complimentary surfaces of the guide rod340.

The arm 394 of the resection block 390 is attached to the base 392 at aheight equal to the lateral side 374 of the bone 314. As such, the arm394 clears the surface of the bone 314 and extends laterally from thebase 392 beyond the aperture 350. In one embodiment, the resection block490 further includes a plurality of adjustments 408 to position the arm394 relative to the depth and location of the aperture 350 as requiredby the individual, physiological features of the bone 314 undergoing thearthroplasty, as shown in FIG. 57A. Thus, one resection block 390 may beinfinitely adjusted and adapted for use with any procedure as required.

The cutting guide block 396 is attached to the end of the arm 394opposite the base 392. The cutting guide block 396 is positioned suchthat a saw blade (not shown) may be inserted through the slot 404 toresect the bone 314 to the depth of the aperture 350. In one embodiment,the resection block 390 further includes a plurality of adjustments 412to position the cutting block guide 396 relative to the depth andlocation of the aperture 350 as required by the individual,physiological features of the bone portions 370, 372, and 374 undergoingresection, as shown in FIG. 57A. In some implementations of the currentinvention, the cutting block guide 396 further comprises a plurality ofapertures for attaching the cutting block guide 396 to the bone 314 viafasteners. In other implementations, a plurality of adjustments permitsremoval of the cutting block guide 396 from the arm 394. Therefore, inone embodiment the cutting block guide 396 is first positioned on andattached to the bone 314 with fasteners to ensure accurate positioning.Following attachment, the cutting block guide 396 is then removed fromthe remainder of the resection block 390 and the resections are made. Assuch, the resections are made accurately and efficiently with minimalcomponentry.

In another embodiment, instrumentation for performing the femoral cutsis inserted into and/or referenced from the final depth of the aperture350. Since the depth of the aperture 350 is the final level for thetibial cuts, all femoral cuts may be accurately referenced from thedepth of the aperture 350. As such, the aperture 350 provides asufficient and relatively non-invasive reference point for the tibia314. Once the femoral cuts are made, the remaining uncut portions of thetibia 314 are then exposed and easily accessible for resection. Inanother embodiment, tensioning devices are combined with the guide rod340, the resection block 390, and the aperture 340 to tension the knee312 as part of the resection procedure. Tensioning devices andprocedures as taught in U.S. patent application Publication Ser. No.11/349,772, entitled GUIDE ASSEMBLY FOR GUIDING CUTS TO A FEMUR ANDTIBIA DURING A KNEE ARTHROPLASTY, filed Feb. 8, 2006 (now U.S. Pat. No.7,927,336), and U.S. patent application Ser. No. 12/191,245, entitledSYSTEMS AND METHODS FOR GUIDING CUTS TO A FEMUR AND TIBIA DURING A KNEEARTHROPLASTY, filed Aug. 13, 2008 (now U.S. Pat. No. 8,303,597), may beeasily combined with the present device 310, and are incorporated hereinby reference, in their entirety. Modifications to the instrumentationand bone 314 are discussed in connection with FIG. 57B, below.

Referring now to FIG. 57B, an implementation of a resection block isshown as combined with the first end 344 of the guide rod 340. In thisembodiment, the post portion or the second end 342 of the guide rod 340is removed from the first end 344 and replaced with a resection blocksystem 440. The resection block system 440 includes an integrated base442 and arm 444, as well as a sled-style cutting guide block 450. Thebase 442 is disk-shaped having a diameter slightly less than thediameter of the aperture 350. The arm 444 extends laterally outward fromthe base 442 in the same plane as the base 442. As such, a portion 460of the bone 314 must be removed to provide a pathway for the arm 444. Inone embodiment, a rongeur or other surgical device is used to remove thebone portion 460 to create the pathway. Once the bone portion 460 isremoved, the first end 344 of the guide rod 340, with the attachedsystem 440, is repositioned within the IM canal 348. The cutting guideblock 450 is then slid over the distal end 446 of the arm 444 andpositioned against the bone 314. At this point, the cutting guide block450 is securely attached to the bone via fasteners and the requiredresections are made via the slot 404. In one embodiment, the cuttingguide block 450 further includes means for releasing the guide block 450from the arm 444 while the guide block 450 is fastened to the bone 314.For example, an upper portion 452 of the guide block 450 may be adaptedto be removable thereby releasing the lower, fastened half of the block450 from the remainder of the system 440.

In an alternate embodiment, the cutting guide block 450 is first slidover the distal end 446 of the arm 444 so that the slot 404 of the guideblock 450 aligns with femur 316 rather than with the tibia 314. In thisconfiguration, the guide block 450 is positioned, relative to the depthof the aperture 350, to make the femoral cuts. Thus, the aperture 350 ofthe tibia 314 acts as a reference point to accurately make the femoralcuts. Once the femoral cuts have been made, the guide block 450 isremoved and repositioned to make the tibial cuts, as previouslydiscussed.

Referring now to FIGS. 58 and 59, various perspective views ofimplementations of the milling bit 320 are shown. Of particular note arethe various configurations of removable blades 332. The removable blade332 is attached to the cutting head portion 322 via a set of screws 410.As such, the blade 332 is easily removed from the bit 320 to allowsharpening and/or replacement of the blade 332. As shown in FIG. 58,some implementations of the removable blade 332 include a single window336 and a single cutting edge 334. As shown in FIG. 559, someimplementations of the removable blade 332 include multiple windows 336and multiple cutting edges 334.

Referring now to FIG. 60, an implementation of a bone milling device 420is shown. Unlike the previously discussed bone milling device 310, thepresent device 420 combines all of the elements of the bone millingdevice 310 into a singular unit 420. The bone milling device 420comprises a guide rod 422, a cutting head portion 424, and a shank 426.The guide rod 422 is sized and adapted to rotatably insert within theopening 346 of the bone 316. The guide rod 422 thereby aligns anddirects the cutting head portion 424 into the opening 346 of the bone346. The shank 426, as previously discussed, couples the milling device420 to a drill (not shown) or other means for rotating the millingdevice 420.

The cutting head portion 424 includes a plurality of annularly situatedcutting teeth 430. Unlike the cutting edge 334 of the previousembodiments, the cutting teeth 430 provide a corrugated surface ofsharpened edges that extend radially outward from the guide rod 422.Thus, the cutting teeth 430 contact and grind the adjacent surfaces ofthe opening 346 to level or knock down any inconsistent features orridges of the bone 316 surface. As such, the cutting teeth 430 provide auniform surface having a diameter equal to the diameter of the cuttinghead portion 424. The milling device 420 is useful where a level andconsistent bone surface is required adjacent to the opening 346. In someimplementations of the milling device 420, the cutting head portion 424includes a plurality of cutting edges and windows to form an aperture inthe bone 316.

While the described systems and methods for using the bone millingdevice 310 can be modified in any suitable manner, in some embodiments,the bone milling device is operated by one or more robots, robotic arms,laparoscopic devices, and/or other automated devices. In suchembodiments, the automated device can cut make cuts in the tibia and/orfemur with or without the use of a guide rod (e.g., guide rod 340, guiderod 422, etc.). Indeed, in some embodiments, the automated device isable to stabilize the knee and to use the bone milling device to cutportions of the tibia and/or femur without the use of a guide rod thatextends up into the bone milling device during resection.

Where an automated device (e.g., a robot arm comprising the describedbone milling device 310 and/or any other suitable device) is used to cuta portion of the tibia and/or femur, the automated device can cut anysuitable portion of the tibia and/or femur. Indeed, in some embodiments,the automated device 280 is configured to cut the aperture 350 into thetibia (see e.g., FIG. 61).

Although in some such embodiments, after the aperture has been cut inthe tibia by the automated device 280, a person then uses a cuttingdevice (e.g., a bone saw) to remove the bone around the periphery of theaperture 350 at the proximal end of the tibia down to a final depth ofthe aperture, in some other embodiments, the automated device uses themilling tool 310 (and/or any other suitable cutting tool) to remove thebone around the periphery of the aperture. In such embodiments, theautomated device can remove the peripheral bone in any suitable manner,including, without limitation, by cutting from side to side across theproximal end of the tibia (e.g., with the milling device and/or anyother suitable cutting tool); by lifting the milling tool (or othercutting device) between cuts and then forcing it distally into the bonearound (and/or overlapping with) the aperture, down to the depth of theaperture; and/or in any other suitable manner that removes bone from theproximal end of the tibia to allow for implantation of a tibialprosthesis.

In some embodiments, the automated device 280 is further configured touse the milling tool 310 (and/or any other suitable cutting device) tomake one or more cuts to the distal end of the femur. In some suchembodiments, the diameter of the cutting head portion 322 of the millingtool is configured to be substantially equal to and/or greater than amedial-lateral width of each individual condyle that it will be used tocut. Accordingly, in some embodiments, when the milling tool is placedinto contact with a portion (e.g., a center and/or other portion) of afemoral condyle and spun, the milling tool will cut a flat surface intothe femoral condyle. Thus, in some embodiments, the automated deviceuses the milling tool (and/or any other suitable cutting device) toresect a distal portion of a femur's medial and/or lateral condyle tocreate one or more distal cuts on the femur. In some embodiments, theautomated device is further configured to use (and the described methodsfurther comprise using) the bone milling device (and/or any othersuitable cutting device) to make an anterior chamfer cut, an anteriorcut, a posterior chamfer cut, and/or any other suitable cut to one orboth of the femur's condyles. Additionally, while the posterior cut canbe made in any suitable manner, including, without limitation, throughthe use the automated device and the bone milling device, in some otherembodiments, a surgeon cuts the proximal cut (and/or any other suitablecut or portion of a cut) manually (e.g., via a bone saw, a chisel,and/or in any other suitable manner). Again, while the automated devicecan use a guide rod (e.g., as discussed above) to make any cut, in someembodiments, the automated device is configured to perform its cutswithout the use of a guide rod that extends into the milling tool.Additionally, while the automated device can be used with any of theassemblies illustrated in FIGS. 1-48 to balance a gap and/or obtain adesired tension between the tibia and femur, in some embodiments, theautomated device (and/or another computer device) is configured tobalance the gap between the tibia and femur without the use of any ofthe other tensioning components set forth herein.

Spacers and Baseplate

In addition to the foregoing, some embodiments of the described systemsand methods further include one or more wedges, blocks, and/or otherspacers that are configured to be inserted in between the femur and thetibia in a knee joint to apply tension to one or more of the kneejoint's ligaments (e.g., the lateral collateral ligament, the medialcollateral ligament, the posterior cruciate ligament, and/or any othersuitable ligament, ligaments, tendon, and/or tendons), to balanceligament (and/or tendon) tension in the knee joint, to properly alignthe tibia and/or femur for resection, to support and/or properly place acutting guide block, and/or to otherwise prepare the knee joint forresection and/or implantation of one or more prostheses. Indeed, as itmay be difficult to apply a proper amount of tension to multipleligaments (for instance, to three or more) in a knee joint at a time, insome embodiments, the described spacers can help apply a desired amountof tension to each desired ligament in a knee joint to ensure the kneejoint is properly balanced and/or aligned when the knee joint is inflexion and/or extension.

With respect to the spacers, the spacers can have any suitablecharacteristic that allows them to function as described herein. Indeed,the spacers can be any suitable shape, including, without limitation,being: wedged-shaped, block-shaped, a rectangular prismatic shape, prismshaped, tubular prism shaped, cup-shaped, dish-shaped, disk-shaped,U-shaped, V-shaped, circular, semi-circular, pill-shaped, bean-shaped,shaped to roughly correspond to the shape of a proximal end of a tibia,symmetrical, asymmetrical, regular, irregular, polygonal, and/or anyother suitable shape that allows them to be used to apply a desiredtension to one or more ligaments in a knee and/or to maintain a desiredgap in the knee.

In some embodiments, the spacer comprises a disc-like (orsemi-disc-like) object. Additionally, while some embodiments of such aspacer comprise a flat face for contacting the proximal end of the tibiaand/or a flat face for contacting the distal end of the femur in a kneejoint, in some other embodiments, the proximal face of the spacer (orthe side that is to face the femur) comprises one or more depressions,indentations, concavities, and/or other recesses that are eachconfigured to cradle a femoral condyle. Although some embodiments of thespacer comprise one flat face and an opposing face defining a recess, insome other embodiments, the spacer comprises two opposing faces thateach define a recess (not illustrated).

In other examples of suitable spacer shapes, FIGS. 62C-62E show that, insome embodiments, the spacer 500 comprises a strip of material (e.g., aleaf spring, a piece of resilient plastic, and/or any other suitablematerial) that is formed into a U-Shape, a V-shape, a wedge shape, awedge shape having a recessed surface for cradling the femur (see e.g.,FIG. 62E), and/or any other suitable shape that allows it to act as aspacer, and to apply pressure (e.g., as a spring), between a tibia and afemur when it is disposed in the knee joint.

In still other examples of suitable spacer shapes, FIGS. 62F-62Jillustrate some embodiments in which the spacer 500 has (from a sideview) a wedge shape (see e.g., FIG. 62I), a wedge portion and a portionconfigured to cradle a distal portion of a femur (see e.g., FIG. 62F), awedge portion and a plateau portion to support the distal portion of thefemur (see e.g., FIGS. 62G and 62H), and a portion that is configured tocradle the distal portion of the femur (see e.g., FIG. 62J, whichillustrates one embodiment of the spacer 500 when viewed from a side oran embodiment of the spacer when viewed from its anterior or posteriorend).

In still other examples of suitable spacer shapes, the spacer 500 canhave any suitable shape when viewed from a top or bottom view thatallows the spacer to function as intended. In this regard, FIGS. 62K-62Nillustrate some non-limiting examples of plan views of some embodimentsof the spacer 500. Additionally, while the spacer can have any suitableprofile from an end view, FIGS. 62O-62R illustrate some non-limitingembodiments of spacer 50 profiles (e.g., as viewed from an anterior endof the spacers, or an end that is configured to be placed adjacent to ananterior portion of a knee).

In yet additional examples of suitable shapes, FIGS. 76A-76H show someembodiments in which the spacer 500 is substantially cuboidal and/orprismatic in shape. In such embodiments, the spacer can have anysuitable prismatic shape, including, without limitation, a substantiallyrectangular, square, parallelepiped, trapezoidal, pyramidal (having aflattened and/or recessed top section), and/or any other suitableprismatic shape. Indeed, FIGS. 76A-76H show some embodiments in whichthe spacers 500 are substantially rectangular prism shaped.

In some embodiments, one or more ends, corners, and/or edges of thespacer 500 are angled, notched, rounded, wedge-shaped, pointed,narrowed, and/or otherwise shaped to help the spacer be inserted betweenthe femur 11 and the tibia 12 relatively easily. By way of non-limitingillustration, FIG. 76B shows an embodiment in which a posterior end 501of the spacer 500 (or an end of the spacer that is configured to bedisposed posteriorly in the knee joint) is missing a corner and/or has arounded or angled edge 499.

The spacer 500 can be any suitable size that allows it to apply adesired tension to one or more ligaments in the knee joint. In someembodiments, the spacer has a maximum height (e.g., a maximum distancethat it is to separate the tibia from the femur; also referred to as H1,as shown in FIG. 62I) of between about 1 mm and about 15 mm (or anysubrange thereof). Indeed, in some embodiments, the spacer has a maximumheight between about 3 mm and about 14 mm (e.g., between about 5 mm andabout 12 mm). Additionally, in some embodiments, spacers are made with avariety of maximum heights (e.g., for use in lateral and medial gaps,for use on patients of different sizes, and/or for any other suitablepurpose). Additionally, although in some embodiments, the same sizedspacers are used on both the lateral and medial sides of the knee joint,in some other embodiments (e.g., as shown in FIGS. 76A-76C, 76E, 76G,76H, 78, and 79), the height of the spacers 500 vary between the lateraland medial sides. Thus, in some embodiments, the described systems andmethods allow for asymmetrical spacer use (or the use of different sizedspacers on the lateral and medial sides of a knee joint).

While the spacer 500 can have any suitable minimum height (e.g., aminimum distance that it is to separate the tibia from the femur when itis inserted between them in the knee joint; as referred to as H2, asshown in FIG. 62I), in some embodiments, the spacer's minimum height isbetween about 0.1 mm and about 15 mm (or any subrange thereof). Indeed,in some embodiments, the spacer has a minimum height of between about 2mm and about 12 mm (e.g., between about 2.5 and about 10 mm).Additionally, in some embodiments, spacers are made with a variety ofminimum heights (e.g., for use in lateral and medial gaps, for use onpatients of different sizes, and/or for any other suitable purpose).Moreover, in some embodiments (as described below), the spacer can bemodified to adjust its maximum and/or minimum height (via one or moresprings, adjustment mechanisms, and/or in any other suitable manner).Although in some embodiments, the minimum height H2 is shorter than themaximum height H1, in some other embodiments (e.g., as shown in FIG.76A), the maximum height H1 and minimum height H2 of the spacer aresubstantially equal.

The spacer 500 can be any suitable length that allows it to function asintended. Indeed, in some embodiments, the spacer has a length (e.g., alength of a portion of the spacer that is configured to be in contactwith at least one of the femur, the tibia, and/or the tibial baseplate(discussed below) when the spacer is inserted between the tibia andfemur) of between about 1 cm and about 12 cm (or any subrange thereof).Indeed, in some embodiments, the spacer is between about 1 cm and about4 cm long (or any sub-range thereof). Moreover, in some embodiments, thespacer has a width (e.g., a width of a portion of the spacer that isconfigured to be in contact with at least one of the femur and the tibiawhen the spacer is inserted there between) of between about 0.5 cm andabout 12 cm (or any sub-range thereof). Indeed, in some embodiments, thespacer is between about 5 mm and about 2 cm wide (or any sub-rangethereof).

Additionally, the spacer's external surface can have any texture thatallows the spacer 500 to function as intended. In some embodiments, thespacer includes one or more smooth surfaces that allow a portion of thefemur and/or the tibia to articulate against the spacer as the kneejoint is moved through its range of motion. Indeed, in someimplementations, a proximal side of the spacer comprises a smootharticular surface that is configured to allow a distal end of the femurto articulate against it as the knee joint moves through a range ofmotion. Accordingly, in some such embodiments, the spacer can be used toprovide a desired tension throughout at least a portion of the knee'srange of motion.

In some other embodiments, the spacer 500 comprises one or morenon-smooth surfaces. Some non-limiting examples of such non-smoothsurfaces include one or more surfaces comprising one or more roughenedtextures, spongiosa metals (and/or other material), knurled textures,barbs, ridges, processes, zig-zag surfaces, cog-like surfaces, porouscladding, external frames, spikes, external matrices, pins, and/or anyother suitable surfaces and/or components that are configured to helpprevent the spacer from sliding out from between the femur and tibia. Byway of non-limiting illustration, while FIG. 62A shows an embodiment inwhich the spacer's proximal face 502 is substantially smooth (e.g., toallow for the femur to articulate against it), FIG. 62B shows anembodiment in which the distal face 506 of the spacer 500 (or the facethat is configured to face the tibia) comprises a plurality of ridges508 that are configured to help prevent the spacer from sliding on thetibia as the spacer is used. In some other embodiments, however, theproximal face of the spacer comprises a spiked, ridged, knurled, and/orother roughened texture to help prevent the spacer from sliding withrespect to the femur.

Although, in some embodiments, the spacer 500 comprises a singlemonolithic object (e.g., an object that is configured to rest directlyon the tibia and/or on a tibial baseplate), in some other embodiments(e.g., as illustrated in FIGS. 63A-63E and 62C-62E), the spacercomprises one or more components that: (i) couple together to formand/or (ii) are resiliently formed and/or coupled together as, thespacer. Indeed, in some embodiments, the spacer comprises a proximalportion that is configured to contact a distal portion of the femur anda distal portion that is configured to contact a proximal portion of thetibia (and/or a tibial baseplate, as discussed below) when the spacer isinserted into the knee joint.

In some embodiments in which the spacer 500 does not just consist of asingle monolithic component, the spacer optionally comprises one or moresprings and/or other biasing mechanisms that are configured to force thedistal and proximal portions of the spacer apart so as to apply aconsistent and/or constant pressure to the femur and the tibia wheninserted into the knee joint. By way of non-limiting illustration, FIGS.63A-63E show some non-limiting embodiments in which the spacer 500comprises a proximal portion 510 and a distal portion 512 that arecoupled together.

In some embodiments, the spacer 500 further comprises one or moremechanisms for biasing the proximal portion 510 and the distal portion512 apart. In this regard, the proximal and distal portions can bebiased apart in any suitable manner, including, without limitation,through the use of one or more springs, elastomeric materials, rubberbands, and/or other resilient materials. By way of non-limitingillustration, FIGS. 63A-63D show some embodiments in which the spacer500 comprises one or more springs 514.

In some embodiments, the spacer 500 is further configured to identifythe pressure that it exerts on the tibia and/or the femur when thespacer is placed in between the two in a knee joint. In this regard, thespacer can be configured to determine the pressure it places on thetibia and/or femur in any suitable manner. Indeed, in some embodiments,the spacer comprises one or more pressure transducers, gauges, and/orother pressure sensors. In this regard, some examples of such pressuresensors include, but are not limited to, one or more piezoresistivestrain gauges, capacitive pressure sensors, diaphragm pressure sensors,electromagnetic pressure sensors, piezoelectric sensors, opticalpressure sensors, potentiometric sensors, pressure gauges, and/or anyother suitable pressure sensors.

By way of non-limiting illustration, FIGS. 63E-63G illustrate someembodiments in which the spacer 500 comprises one or more pressuresensors 516 that are configured to measure pressure that is applied to adistal end of the femur. In accordance with some such embodiments, whenthe spacer is inserted between the tibia and the femur, the knee jointis able to move through a range of motion (e.g., with the distal end ofthe femur articulating against the proximal portion 510 of the spacer)such that tension in the knee joint can be measured throughout the rangeof motion and not just when the knee is at 0 degrees and/or 90 degrees.Additionally, in some embodiments, a first spacer is placed at a lateralside of the knee joint and a second spacer is placed at a medial side ofthe knee joint such that pressure can be measured at the medial andlateral sides of the knee throughout a range of motion of the knee.

Where the spacer 500 comprises one or more pressure sensors 516, thesensors can communicate their sensor readings in any suitable manner,including, without limitation, wirelessly, via one or more wiredconnections (see e.g., a wired connection 518 in FIG. 63E), via ananalog display and/or mechanism, via an LCD and/or other display on thespacer (or elsewhere), and/or in any other suitable manner. In someembodiments, however, the spacer is configured to communicate sensorreadings via a wired connection. Accordingly, by limiting the hardwarethat is disposed in the spacer, the overall price of the spacer can bereduced while the lifespan of the spacer can, in some embodiments, beincreased (or even reduced, for disposable spacers).

In some embodiments, instead of (or in addition to) having a pressuresensor, the spacer 500 uses one or more mechanical mechanisms todetermine an amount of tension in the knee joint. Accordingly, in someembodiments, when a first spacer is placed in a lateral side of the kneejoint and a second spacer is placed in a medial side of the knee joint,a practitioner and/or computer device can determine whether or nottension in the knee joint is balanced and/or is otherwise proper. Insuch embodiments, the spacer can comprise any suitable mechanicalmechanism that is capable of indicating a tension and/or pressure in theknee joint. In this regard, FIGS. 63A, 63B, 63C, 63D, 63F, and 63H showsome embodiments in which the spacer 500 comprises one or more springs514 that are used to indicate a pressure exerted on the spacer. In suchembodiments, the springs can be used to measure (and/or to otherwiseindicate) pressure in the knee joint in any suitable manner. By way ofnon-limiting example, FIGS. 63C-63D show that, in some embodiments, thespacer 500 comprises a spring 514 and/or other resilient material and agauge 520 that are configured to indicate a pressure and/or tensionmeasurement.

In another non-limiting example, some embodiments of the spacer 500 arecalibrated such that one portion of the spacer (e.g., the proximalportion 510, a stop, and/or any other suitable component) contactsanother portion (e.g., the distal portion, a stop, and/or any othersuitable component) when a set pressure is reached. By way ofnon-limiting illustration, FIGS. 63A and 63H show that, in someembodiments, the spacer 500 is configured to have a stop 522 contact thedistal portion 512 of the spacer when a set amount of pressure isapplied to the proximal portion 510 of the spacer.

In another non-limiting illustration, FIG. 63B shows that, in someembodiments, the spacer 500 is configured to have the proximal portion510 contact the distal portion 512 when a set amount of pressure isapplied to the proximal portion 510 of the spacer. Additionally, theskilled artisan will recognize that, in accordance with someembodiments, when the proximal portion 510 of the spacer 500 in FIG. 63His forced against the distal portion such that a portion of the proximalportion 510 (in addition to the stop 522) contacts the distal portion512, more pressure is being applied to the spacer than desired (e.g.,indicating that the knee is under more tension than desired).

In some knee arthroplasties, the gaps between the tibia and femur aredifferent on the lateral and medial sides of the knee joint (e.g., inflexion and/or otherwise). Accordingly, in some embodiments, the spacers500 are configured such that a different sized spacer is used on themedial and the lateral sides of the knee joint. Indeed, in someembodiments, a taller spacer (or a spacer having a taller lateral side)is used on the lateral side and a shorter spacer (or a spacer having ashorter medial side) is used on the medial side of the knee joint (orvice versa). In some embodiments in which a medial and a lateral spacerhave different heights and in which one portion of the spacer isconfigured to contact another portion of the spacer when a desiredpressure is obtained between the tibia and the femur, the differentlysized spacers (and/or a spacer having differently sized medial andlateral portions) are calibrated to exert similar pressures, and toindicate (e.g., via the contacting of a first portion with a secondportion of each of the spacers and/or otherwise) that the same desiredpressure has been achieved in each side of the knee.

The spacers 500 can each be configured to indicate that any desiredpressure has been achieved. In some embodiments, such a desired pressurecan be between about 1 and about 40 inch pounds of force (or anysub-range thereof). Indeed, in some embodiments, a first portion of eachspacer is configured to contact a second portion of each spacer when apressure between about 10 inch pounds and about 25 inch pounds (e.g.,between about 15 and about 21 inch pounds) is applied to the spacers.

In some embodiments, the spacer 500 is configured to be used with anysuitable conventional and/or novel method of joint arthroplasty. In someembodiments, one or more spacers are configured to be used to balancegaps between the tibia and femur, to apply desired tensions totendons/ligaments in the knee joint, and or to otherwise prepare theknee for resection, without necessarily requiring any other bonespreaders, tensioning assemblies, and/or other devices to separate thetibia from the femur for gap and ligament balancing. By way ofillustration, FIGS. 64A-64D illustrate some embodiments in whichmultiple spacers 500 are used to properly balance the knee joint inpreparation for resection (e.g., by resting directly on the tibia and/orotherwise). In this regard, any suitable spacer can be used to balancethe knee joint, including, without limitation, those spacers 500 shownin FIGS. 65A-65E.

In some other embodiments, however, one or more spacers 500 areconfigured to be used with one or more other apparatuses (i.e., one ormore of the apparatuses, systems, and/or methods described herein) toprepare a knee for resection. Indeed, in some embodiments, one or morespacers are configured to adjustably couple to one or more of thecomponents described herein, including, without limitation, to thetibial mount 23, the tibial tensioning adapter 160, the plateau flanges28, the femoral mount 15, a cutting guide (e.g., cutting block, guide,assemblies, etc., such as cutting accessories 52, 54, and 87), and/orany other suitable component that allows the spacers to be selectivelyheld in place while being disposed in the knee joint.

By way of non-limiting illustration, FIGS. 65F-65I and 76A show that, insome embodiments, one or more spacers 500 are configured to couple inthe knee joint via one or more tibial baseplates 530 and/or other tibialcomponents (which can be for uni-compartmental and/or full kneereplacement). Additionally, FIGS. 66A and 66B show that, in accordancewith some embodiments, the spacers 500 (not shown in FIGS. 66A-66B) areconfigured to couple to one or more tibial baseplates 530, tibialtensioning adapters 160, and/or other tibial components.

Where the spacers 500 are configured to couple to one or more of thedescribed apparatuses and/or systems (e.g., to one or more tibialbaseplates 530 and/or other tibial components), the spacers can becoupled to such apparatuses and/or systems in any suitable manner,including, without limitation, via one or more mechanical engagements,frictional engagements, slides, guides, rails, magnets, grooves with oneor more slidably mating objects, cables, by being configured to have onecomponent rest on the other such that one component can be moved inmedially, laterally, posteriorly, and anteriorly with respect to theother component, and/or via any other suitable coupling mechanism. Byway of non-limiting illustration, FIGS. 65F-65I, 71A-75C, and 76A showthat, in some embodiments, the tibial component (e.g., tibial baseplate530) comprises one or more slots or other recesses 532, and the spacers500 each comprise one or more corresponding projections 534 that areconfigured to slidably mate with the slots. In some such embodiments,the tibial baseplate is configured to couple with one or more spacers ofdifferent size and/or having one or more other varied characteristics.Accordingly, in some such embodiments, a user can readily place one ormore baseplates on the tibia (e.g., by setting the base plate on thetibia, connecting the baseplate to the tibia via one or more fasteners529 (e.g., via hole 531) or in any other suitable manner) and thenselectively place one or more different sized spacers on the baseplateuntil a proper balance and/or alignment is achieved in the knee joint.Of course, while FIGS. 65F-65I, 71A-75C, and 76A show some embodimentsin which the tibial baseplate 530 defines one or more elongated recesses532 and the spacers 500 comprises one or more elongated projections 534,in some other embodiments, the tibial baseplate comprises one or moreelongated projections and the spacers comprise one or more correspondingrecesses.

Where the tibial baseplate 530 comprises one or more grooves, recesses,rails, guides, and/or is otherwise configured to guide (and/or retain)one or more spacers to (or in) a desired position on the baseplate, thebaseplate can comprise any suitable configuration that allows it tofunction in such a manner. Indeed, in some embodiments, the baseplatecomprises one or more guides or couplings (e.g., grooves, rails,openings, etc.) that extend (and/or are disposed) in any suitabledirection (e.g., in an anteroposterior direction, in a medial-lateraldirection, at an angle, and/or in any other suitable direction withrespect to the baseplate). For instance, FIG. 73A shows an embodiment inwhich the tibial baseplate 530 comprises two elongated recesses 532 thatrun substantially in an anteroposterior direction. Additionally, whilethe various guides or couplings on the tibial baseplate can have anysuitable relationship to each other (e.g., being perpendicular to eachother, being at an angle to each other, being disposed at the same ordifferent heights on or in the tibial baseplate with respect to eachother, and/or having any other suitable relationship), FIG. 73A showsthat, in some embodiments, the tibial baseplate 530 comprises multipleelongated recesses 532 (or spacer and/or trial tibial component guidesor couplings) that run substantially parallel with each other.

In some embodiments, in which the spacer 500 is configured to couple toanother object in the knee joint (e.g., the tibial baseplate 530), thespacer is configured to be adjustably moved and retained in one or moredesired positions (e.g., via one or more adjustment mechanisms, clamps,pins, racks and pinions, locking mechanisms, ratchets, pawls, guides,slides, friction fittings, mechanical mechanisms, pressure from the kneejoint, and/or other suitable mechanisms). Accordingly, in someembodiments, the spacers are configured to be selectively pushed deeperinto and/or to be removed from the knee joint and to be selectivelyretained in a desired position to change and/or maintain tension in theknee joint.

Although some embodiments of the spacer 500 comprise no handle, someother embodiments, comprise one or more handles that are configured tohelp a user readily manipulate the spacer, even when the spacer isdisposed in the knee joint. In this regard, the handle can connect tothe spacer in any suitable manner, including, without limitation, viaone or more catches, mechanical engagements, frictional engagements,magnetic engagements, threaded engagements, holes in the spacer thatreceive a portion of the handle, barbs, hooks, and/or in any othersuitable manner. By way of non-limiting illustration, FIGS. 68A-68H and79 illustrate some embodiments in which the spacers 500 comprise one ormore openings 536 that are configured to receive one or more portions ofa handle 538. Accordingly, in some such embodiments, the handle can beused to push the spacer into a desired position in the knee joint, andthe handle can then be removed to prevent it from encumbering the kneejoint.

While, in some embodiments, the handle 538 is permanently coupled with aspacer 500, in some other embodiments, the spacer and its correspondinghandle are configured to selectively couple to and/or decouple from eachother in any suitable manner, including, without limitation, by having aprojection at an end of the handle fit into an opening 536 at ananterior portion (and/or any other suitable portion) of the spacer, viaone or more catches, one or more magnets and/or magnetic materialsdisposed in the handle and the spacer, and/or in any other suitablemanner. Indeed, in some implementations, an anterior portion of thespacer defines an opening that is configured to receive a projection 539(e.g., FIG. 79) at an end of the handle. In some such embodiments, thehandle's projection comprises a extension member (not shown) that isconfigured to extend into a corresponding opening in the recess of thespacer (e.g., when the handle is disposed at a certain angle) such thatthe handle can be used to pull the spacer from between the tibia and thefemur.

In some embodiments, the spacers 500 are further configured to supportand/or couple with one or more cutting guides (e.g., cutting accessories52, 54, and/or 87) to direct a cutting tool for resection of a portionof the knee joint. In such embodiments, the spacers can support and/orcouple with the cutting guides in any suitable manner, including,without limitation, through the use of one or more catches, mechanicalengagements, frictional engagements, magnetic engagements, threadedengagements, rails, grooves, magnets, holes in the spacer that receive aportion of the cutting guide, and/or in any other suitable manner. Byway of non-limiting example, in some embodiments, the spacers 500comprise one or more openings 536 that are configured to receive (and/orone or more one or more processes that are configured to be received by)portions of a cutting guide (e.g., the flexed knee cutting guide 54 anddirect mount 106 (as illustrated in FIG. 37) and/or other suitablecutting guide).

In some embodiments, the described systems comprise one or morereference spacers that are configured to dispose the cutting block,guide, and/or assembly, in the proper location. By way of non-limitingillustration, FIGS. 76C-76F show some embodiments in which one or morereference spacers 550 are disposed on the tibial baseplate 530 so as tosupport and/or hold one or more cutting tool guides, blocks, and/orassemblies 555. In this regard, the reference spacers can be used in anysuitable manner to ensure that the cutting assembly 555 is in the rightposition. For instance, FIG. 76D shows that, in some embodiments, thecutting assembly 555 is used with a gauge or marker (which may include acutting blade) 560. In some such embodiments, different sized referencespacers 550 can be used until the marker 560 and/or another portion ofthe cutting assembly 555 is disposed in a desired location. In thisregard, the reference spacers can be any suitable height, length, width,size, and can include any other suitable feature (e.g., handle opening536, chamfered edge, etc.), as discussed above with respect to thespacers (the references spacers being classified as spacers).

Where the described systems and methods optionally allow for the use ofone or more reference spacers 550, such spacers can couple to the tibialbaseplate 530, the cutting assembly 555 and/or any other suitablecomponent in any suitable manner, including, without limitation, via oneor more mechanical engagements, frictional engagements, magnets, slides,guides, rails, grooves with one or more slidably mating objects, cables,by being configured to have one component rest on the other such thatone component can be moved in medially, laterally, posteriorly, andanteriorly with respect to the other component, by resting on thebaseplate, and/or in any other suitable manner. By way of non-limitingillustration, FIG. 76C shows an embodiment in which the reference spacer550 rests on the baseplate 530 and is at least somewhat held in positionby one or more fasteners 529. Additionally, although some embodiments ofthe reference spacer can selectively connect to and disconnect from thecutting assembly, FIG. 76D shows an embodiment in which the cuttingassembly 555 rests on top of the reference spacer 550. In this regard,FIGS. 76D and 76F show that such a configuration can allow the referenceblock (or reference blocks of a variety of sizes) to property align thecutting assembly 555 when the knee joint is in flexion (e.g., as shownin FIG. 76D) and in extension (e.g., as shown in FIG. 76F).

Where one or more spacers 500 are disposed in the knee joint duringresection, the spacers can be used in any suitable manner. Indeed, insome embodiments, the spacers are maintained in the knee joint until oneor more distal cuts of the femoral condyles have been made completely.In some other embodiments, however, one or more spacers are insertedinto the knee joint, and one or more partial distal cuts are made beforethe spacers are removed and the distal cuts are completed.

In some embodiments, the spacers 500 comprise one or more soft tissueretractors, lamina spreaders, spreaders, reverse pliers, levers, and/orany other suitable device that is capable of being used to separate thefemur 11 from the tibia 12 in the knee joint. Indeed, in someembodiments, one or more retractors (e.g., soft tissue and/or any othersuitable type of retractors) are attached to any suitable portion of thedescribed apparatuses and/or systems (including, without limitation, toone or more spacers 500, reference spacers 550, tibial mounts 25, tibialbaseplates 530, femoral mounts 15, tibial IM rods 14, femoral IM rods13, plateau flanges 28, secondary femoral mounts 100, tibial tensioningadapters 160, flexion bolts 30, extension bolts 96, gauge blocks 76,bushings 33, valgus adapter members 110, flexion bolts 120, threadedbarrels 115, tibial components, femoral components, tensioningassemblies, ratcheting devices 142, and/or any other suitablecomponents). Accordingly, in some such embodiments, one or moreretractors are coupled (e.g., permanently, selectively, adjustably,and/or otherwise) to one or more of the tibial baseplate, femoral mount,a femoral component, the tibial mount, a tibial component, a tensioningassembly, a cutting block, and/or any other suitable portion of thedescribed apparatuses and/or systems to provide better exposure to thebones in the knee joint while the described systems and methods are inuse. In one non-limiting example, FIG. 65E shows that, in someembodiments, the spacer 500 is configured to have a prominent lateraledge (e.g., at a proximal and/or distal portion) that is configured toserve with and/or as a lateral tissue retractor.

In some other embodiments, one or more retractors (e.g., laminaspreaders, spreaders, reverse pliers, levers, and/or any other suitabledevice capable spreading the femur 11 and the tibia 12) are used toprovide proper tension in the knee joint. By way of non-limitingillustration FIGS. 77A-77D show that in some embodiments one or moremodified and/or standard lamina spreaders 565 are used as spacers 500 toprovide tension to the knee joint. In such embodiments, the laminaspreaders (and/or other suitable retractors) can have any suitablefeature. Indeed, although in some embodiments, the lamina spreaderscomprise any suitable conventional or new lamina spreaders, in someother embodiments, the lamina spreaders (or other retractors) areconfigured to be selectively coupled to and/or decoupled from thebaseplate 530.

Where the lamina spreader 565 (and/or other retractors) can beselectively coupled to and decoupled from the baseplate 530, thespreaders can be coupled to the baseplate in any suitable manner,including, without limitation, via one or more: processes that areconfigured to mate with a corresponding recess in the tibial baseplate,recesses that are configured to mate with a corresponding process of thebaseplate, mechanical engagements, frictional engagements, magnets,rails, grooves, catches, couplers, and/or other suitable mechanisms. Byway of non-limiting illustration, FIGS. 77E-77F show some embodiments inwhich a pad 570 of the lamina spreader 565 comprises one or moreprocesses 575 that are configured to mate with one or more recesses orcouplings (e.g., holes 531, slots 532, tensioner couplings 533 openings540 (e.g., punch openings or otherwise), and/or any other suitablerecesses) in the baseplate 530. Accordingly, in some such embodiments,the lamina spreaders (or other retractors or spacers) can be relativelyeasy to use and can be retained in place with little worry about themslipping out of the knee joint when the knee joint is under tension—bothwhen the knee is in flexion (e.g., as shown in FIGS. 77A and 77C), whenthe knee is in extension (e.g., as shown in FIGS. 77B and 77D), as wellas when the spreaders are used with one or more block-shaped spacers 500(e.g., reference spacers 550) and or cutting assemblies 555 (e.g., asshown in FIGS. 77C-77D).

The described components can be modified in any suitable manner thatallows them to function as set forth herein. In one example, one or moreof the described components (e.g., the tibial baseplates 530, tibialtensioning adapters 160, and/or any other suitable component describedherein) are configured to serve as a drill bit and/or punch guide toprepare the tibia for a tibial implant. Indeed, in some embodiments, thetibial baseplate defines one or more openings that are configured to beused to ensure proper drill bit and/or punch placement.

By way of non-limiting illustration, FIGS. 84A-84B shows that, in someembodiments, the tibial baseplate 530 defines one or more openings 540that are configured to guide a punch (e.g., a keel punch 544 and/or anyother suitable punch) into the tibia (e.g., to prepare the tibia toreceive a stem from a tibial component and/or for any other suitablepurpose). In such embodiments, the opening can have any suitable shape(e.g., a chevron shape, a boomerang shape, a circular shape, anelliptical shape, a symmetrical shape, an asymmetrical shape, apolygonal shape, and/or any other suitable shape). For instance, FIG.84A shows an embodiment in which the opening 540 comprises a first wing545 and a second wing 546 that allow the opening 540 to extend over amedial and lateral portion of the tibia's proximal end. Additionally,while such an opening 540 can be disposed in any suitable location inthe baseplate, FIG. 84B shows that, in some embodiments, the opening isdisposed substantially in the middle (or the medial-lateral middle) ofthe tibial baseplate 530.

In another example, some embodiments of the tibial baseplate 530 areconfigured to receive one or more trial tibial components such that amedical practitioner can determine the proper size of the permanenttibial component and/or permanent femoral component that should be usedin the knee. In this regard, the trial tibial components can compriseany suitable feature that allows them to function as described herein.Indeed, in some embodiments, the trial tibial components are configuredto be extend over only a medial or a lateral portion of the tibia and tobe used in uni-compartmental arthroplasties. In accordance with someother embodiments, however, FIGS. 74A-74C show that the trial tibialcomponents 585 are configured to be used in total knee replacementsurgeries. Moreover, while some embodiments of the trial tibialcomponents 585 comprise a proximal surface 584 that is substantiallyflat (e.g., as shown in FIGS. 74A-74B), in some other embodiments, alateral and/or medial side of the trial tibial components' proximalsurface is recessed so as to cradle the condyles of a femur and/orfemoral component.

Where the tibial baseplate 530 is configured to couple with one or moretrial tibial components 585, the trial components can couple with thebaseplate in any suitable manner, including, without limitation, via anysuitable coupling and/or guide mechanism (e.g., any of the couplingand/or guide mechanisms discussed above with respect to the spacers500). Indeed, in some embodiments, one or more spacers and trial tibialcomponents are configured to couple to the tibial baseplate via the samecouplings (e.g., elongated recesses 532), though at different times. Byway of illustration, FIGS. 74A and 74C show some embodiments in whichthe trial tibial component 585 comprises one or more processes 534 thatare configured to be received by corresponding recesses 532 in thetibial baseplate 530.

Where the tibial baseplate 530 is used with one or more trial tibialcomponents 585, the trial tibial components can be any suitablethickness (e.g., can have any suitable distance from their distalsurface, which is configured to contact the baseplate, and theirproximal surface, which is configured to contact one or more condyles ofa femur or femoral component). Indeed, in some embodiments, the tibialtrial components have a thickness between about 1 mm and about 3 cm (orany subrange thereof). Indeed, in some embodiments, the trial tibialcomponents have a thickness between about 5 mm and about 1.5 cm.

As another example of a suitable modification, in some embodiments, thetibial baseplate 530 is configured to be used with any suitable known ornovel tensioner and/or other tensioning assembly that is configured tobe actuated (when a knee joint is in flexion and/or extension) to vary adistance between the tibia and femur and/or to allow for changes invarus-valgus angulation between the femur and the tibia when thetensioning assembly is coupled to the tibia (e.g., via the tibialbaseplate) and to the femur (e.g., via a femoral component orotherwise). Indeed, in some embodiments, the tibial baseplate isconfigured to be used with the ratcheting device 142, the extension bolt96, the flexion bolt 30, and/or any other suitable component describedherein. By way of non-limiting illustration, FIGS. 80-82B show someembodiments in which the tibial baseplate 530 is configured to couplewith one or more components of the tensioning assemblies discussedherein (e.g., one or more bushings 125, extension bolts 130, flexionbolts 30, 13 femoral intramedullary rods 13, threaded barrels 115,threaded shafts 121, and/or other suitable components).

Where the tibial baseplate 530 is configured to be used with one or moretensioning assemblies, the tensioning assemblies can couple with thetibial baseplate in any suitable manner, including, without limitation,via one or more mechanical engagements, frictional engagements, magnets,catches, recesses, protrusions, and/or other suitable couplings. Indeed,in some embodiments, the tensioning assembly comprises one or moreprotrusions (e.g., an end of the bushing 125, an end of the extensionbolt 130, etc.) that are configured to extend into one or more recessesand/or openings (e.g., opening 540) in the tibial baseplate. By way ofillustration, FIGS. 80 and 82B show some embodiments in which the tibialbaseplate 530 comprises an opening 540 and one or more other couplings(e.g., tensioner openings 542) that are sized, shaped, and located inspecific positions so as to properly function with one or moretensioning assemblies (including, without limitation, any suitableassembly or component described herein).

As another suitable modification, in some embodiments, one or more edgesof the tibial baseplate 530 comprise one or more recesses, ridges,protrusions, and/or magnets, other catches that allow a user to easilygrab and lift the baseplate from the tibia (e.g., via a finger, a tool,and/or other suitable object). By way of non-limiting illustration, FIG.74A shows an embodiment in which a recessed catch 537 is disposed at ananterior edge of the tibial baseplate 530.

As still another example of a suitable modification, although someembodiments of the tibial baseplate are configured to substantiallycover a resected surface at a proximal end of the tibia (e.g., for fullknee replacements), in some other embodiments, the tibial baseplate isconfigured to extend over only a medial portion or a lateral portion ofthe tibia, so as to be used for uni-compartmental arthroplasties.

In still another example, some embodiments of the tibial baseplate 530comprise one or more fastener holes (e.g., holes 531) that allow one ormore fasteners (e.g., nails, spikes, screws, shafts, etc.) to extendthrough a proximal and distal side of the baseplate and into theproximal end of the tibia. Additionally, while such holes can extendthrough the baseplate at any suitable angle (e.g., being perpendicularor at any other angle with respect to the distal surface of thebaseplate), in some embodiments, the holes are formed at an angle thatguides the fastener in a distal-posterior direction into the tibia(e.g., to allow the fastener to be easily driven in and pulled from thetibia while preventing portions of the knee joint from being undesirablydamaged).

In yet another example, while some embodiments of the tibial baseplate530 and the trial tibial component 585 comprise a rounded notch at theirposterior end, in some embodiments, the notch need not be rounded (e.g.,the notch is squared, comprises a plurality of angled surfaces, etc.) orneed not exist.

The described components can be used in any suitable manner. In thisregard, while the described methods can be reordered, shortened, addedto, comprise substitutions, have various portions of the methods beperformed simultaneously or at different times, and/or otherwise bemodified in any suitable manner, in some embodiments, the methodsincludes resecting a proximal portion of the tibia with one or moreconventional and/or novel instruments (e.g., the bone milling device 310and/or an automated device).

In some embodiments, after the tibia is resected, a trial baseplate(e.g., tibial baseplate 530, which can be used for tensioning ligamentswith a tensioning assembly, balancing the gaps (e.g., with spacers 500),guiding a keel punch 544 or other punch, testing trial tibial components585, and/or for any other suitable purpose) is placed on the tibia(e.g., is set on the tibia, is attached to the tibia with one or morefasteners 529, or is otherwise placed on the tibia).

In some cases, when the knee is flexed, different sized spacers 500 arecoupled to the tibial baseplate 500 (e.g., as shown in FIG. 76A) toadjust ligament tension and/or to balance gaps in the knee joint. Insome cases, a tensioning assembly (e.g., as described herein) is used(e.g., as a leg holder to hold the knee flexed and as a lift to hold thefemur and tibial apart for exposure of the posterior knee) to facilitatemedial and/or lateral balancing, and the knee joint is balanced (e.g.,via one or more spacers 500 and/or other devices discussed herein).

In some cases, the method continues as one or more reference blocks 550are placed on the baseplate 500 (e.g., as shown in FIG. 76C). In thisregard, any suitable size of reference block can be used (e.g., asdiscussed above). For instance, if a resection block is chosen thatcorresponds to a 9 mm, 11 mm, 13 mm, or 16 mm tibial implant, in someembodiments, 8 mm (or any other suitable amount of bone will be resectedfrom the “tight” side of the joint (often the medial side, though itcould be taken from the lateral and/or the medial side)).

In some embodiments, the method continues as a cutting assembly 555 isplaced on the reference block 550 (e.g., as shown in FIG. 76D). In somesuch cases, such a cutting assembly can be used to make most, if notall, femoral bone resections. Additionally, in some embodiments, thecutting assembly is selected such that it is configured to guide ananterior femoral resection at a level of an anterior cortex of thefemur. In some cases, the cutting assembly is angled to be substantiallyperpendicular to a flexion angle of the distal femur.

In some instances, once the preliminary anterior femoral resection ismade by cutting in line with a top guide of the cutting assembly 555(e.g., as shown in FIG. 76D), a posterior femoral resection is made (seee.g., FIG. 76E) to set the flexion gap. Alternatively, the posteriorfemoral resection is made after the distal resection, to set theextension gap.

In some cases, as the method continues, the knee joint is placed intoextension and spacer 500 blocks are placed in the knee joint on thetibial baseplate 530 (e.g., as shown in FIG. 76E) to adjust ligamenttension and/or to balance the knee joint.

In some cases, a femoral resection reference block 550 is again placedonto the baseplate 500 (e.g., as shown in FIG. 76E). In some such cases,the same thickness reference block that was used for cutting the femur(e.g., as discussed above with reference to FIG. 76D) is used again.

In some embodiments, once the cutting assembly 55 is placed on thereference block 550 (also shown as 500 in FIG. 76F), one or morefasteners are driven through the cutting assembly and into the femur tomaintain the cutting assembly in the proper location on the resectedanterior femur. In instances, the method then continues as the knee isflexed and the distal femoral bone resection is accomplished through aslot in the cutting assembly 555.

In some cases, with the knee flexed, the knee is optionally re-tensionedand/or the flexion gap is balanced (e.g., via shimming with the spacers500 or otherwise). Additionally, in some cases, one or more fasteners(e.g., pins) are placed in the cutting assembly to attach the guide ontothe resected distal femur, with the cutting assembly resting on thereference block 550, and the anterior, posterior, and/or chamber femoralbone resections are made (see e.g., FIG. 76F).

In accordance with some embodiments, instead of completing the processdescribed above with spacers 500 comprising spacer blocks, the method isconducted using one or more retractors 565 and/or lamina spreaders(e.g., as shown in FIGS. 77A-77D).

In some embodiments, once the femoral resections have been made, a trialtibial component 585 is placed on the tibial baseplate 530 and/or atrial femoral component 580 is placed on the femur and the knee joint isevaluated for balance, range of motion, alignment, and/or stability.(See e.g., FIGS. 75D-75E).

In accordance with some embodiments, the method further continues as oneor more stem slots are made in the femur and/or tibia. Indeed, in someembodiments, a stem slot is prepared as a punch, drill, and/or othercutting tool forced down through an opening 540 in the top of thebaseplate 530 (e.g., an opening having a chevron shaped, a roundedshape, an angled slot, an elliptical opening, a circular opening, apolygonal opening, and/or any other suitably shaped opening) (see e.g.,FIG. 84A) and (if screws are to be used) the baseplate serves (in someembodiments) as a template for screw (or other fastener) placement,before the final implants are installed (see e.g., FIG. 70).

Additionally, while the methods described above can be performedmanually, in some embodiments, similar methods are performed with theuse of one or more robots and/or other automated devices. Indeed, insome such embodiments, the methods include using a robot to make atibial resection and then placing the tibial baseplate 530 on theresected tibia. In some such cases, when the knee is flexed, spacerblocks 500 (or retractors 565) are placed in the knee joint and theligament tension is adjusted and the gaps are balanced by shimming themedial and lateral sides independently (see e.g., FIG. 76A). In somesuch cases, the pose of the knee is then captured (e.g., for use by therobot in making resections).

In some cases, the knee joint is also placed in extension and theligaments are again placed in proper tension and the gaps are properlybalanced (e.g., with spacers 500, block spacers and/or retractors).Again, the pose of the knee is captured.

In some cases, a virtual femoral component is adjusted to balance thegaps in flexion and extension. Moreover, in some cases, the robot isused to make one or more of the femoral resections. Following suchresections, a tibial trial component 585 and a trial femoral component580 are seated in the knee joint, and the balance, range of motion,alignment, and/or stability of the knee are tested (e.g., with orwithout aid by computer information gathered by the robot).

In some cases, once the size of the proper tibial and femoral componentsis determined, a punch 544 can be driven through the tibial baseplate530 and the permanent femoral and tibial components can be seated in theknee joint.

The various portions of the described apparatuses and systems can bemade in any suitable manner. In this regard, some non-limiting examplesof methods for making the described apparatuses and systems includeboring, machining, etching, cutting, drilling, grinding, shaping,plaining, molding, extruding, sanding, lathing, smoothing, buffing,polishing, casting, bending, tapping, dying, connecting various pieceswith one or more adhesives, mechanical fasteners (e.g., nails, clamps,rivets, staples, clips, pegs, crimps, pins, screws, brads, threads,brackets, etc.), welds, and/or by melting pieces together; and/or anyother suitable method that allows the described apparatuses and systemsto perform their intended functions.

The various portions of the described apparatuses and systems cancomprise any suitable material, including, without limitation, one ormore metals, metal alloys, plastics, hard plastics, polymers, syntheticmaterials, natural materials, ceramics, and/or any other material ormaterials that are suitable for use in accordance with the describedsystems and methods.

Additionally, the various components described herein can be usedtogether in any suitable combination, with elements from of thedescribed systems, embodiments, methods, and apparatus being mixed andmatched in any suitable manner. By way of non-limiting example, FIGS. 78and 80-83 illustrate some examples of suitable kits, comprising one ormore milling bits 320, guide rods 340, drill bits 341, reamers 343,spacers 500, reference spacers 550, cutting assemblies 555, spreaders565, trial femoral components 580, trial tibial components 585, tibialbaseplates 530, femoral intramedullary rods 13, non-threaded posts 115,flexion bolts 120, and/or extension bolts 130. While some embodiments ofsuch kits have several beneficial features, in some cases, the kitscomprise relatively few pieces. As a result, some such kits arerelatively lightweight, can fit in a relatively small space (e.g., fewerautoclave trays than other competitive systems (e.g., can fit in asingle autoclave tray)), and are relatively inexpensive.

Indeed, the various components, systems, and methods described hereincan have several beneficial characteristics. For instance, someembodiments of the described systems and apparatus can be used withmanual, power, and/or robotic tools and instrumentation. Additionally,some embodiments of the described systems and apparatus can be used toperform an entirely extramedullary gap balanced total knee arthroplastyand/or uni-compartmental knee arthroplasty.

As yet another example of a beneficial characteristic, one or morecomponents of some embodiments of the described systems and methods areconfigured to be used with new and/or updated technology. By way ofnon-limiting example, the described tibial baseplate 50 can be used witha variety of new and conventional spacer 500, retractors (e.g., laminaspreaders 565), tensioning assemblies, trial tibial components 585,punches, fasteners, robotic equipment, and/or any other suitablecomponents. Similarly, the described tensioning assemblies, trial tibialcomponents, punches, fasteners, robotic equipment, and other any othercomponents or apparatus described herein can be used with any new andsuitable tibial baseplates and/or other suitable components.

As still another example of a beneficial characteristic, in someembodiments, one or more of the described components comprise one ormore disposable materials. Indeed, in some embodiments, the spacers 500,trial tibial components 585, tensioners and/or tensioning assemblies,trial tibial components, trial femoral components, and/or othercomponents or apparatus described herein can be disposable and/orpackaged separately (e.g., from different components and/or from similarcomponents of different sizes).

Thus, as discussed herein, the embodiments of the present inventionembrace technologies and methods for accurately milling a bonepreparatory to an arthroplasty procedure. As will be appreciated by oneof skill in the art, the present invention may be embodied in otherspecific forms without departing from its spirit or essentialcharacteristics. For example, in some embodiments the present inventionis modified for use in a uni-compartmental knee arthroplasty procedure.In another embodiment, the present invention is modified for use in atotal knee arthroplasty procedure. The described embodiments are to beconsidered in all respects only as illustrative and not restrictive. Thescope of the invention is, therefore, indicated by the appended claimsrather than by the foregoing description. All changes that come withinthe meaning and range of equivalency of the claims are to be embracedwithin their scope.

Many modifications and other embodiments of the inventions set forthherein will come to mind to one skilled in the art to which theseinventions pertain having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. Therefore, it is tobe understood that the inventions are not to be limited to the specificembodiments disclosed and that modifications and other embodiments areintended to be included within the scope of the appended claims.Although specific terms are employed herein, they are used in a genericand descriptive sense only and not for purposes of limitation.

What is claimed is:
 1. A tibial baseplate, comprising: a tibialbaseplate having a first surface and a second surface that issubstantially opposite to the first surface, the first surface beingconfigured to be seated on a resected surface at a proximal end of atibia, wherein the tibial baseplate defines a keel punch guide whichincludes a first wing that is configured to extend over a lateralportion of the proximal end of the tibia and a second wing that isconfigured to extend over a medial portion of the proximal end of thetibia when the tibial baseplate is seated on the resected surface at theproximal end of the tibia.
 2. The baseplate of claim 1, wherein thetibial baseplate further comprises a first coupling that is configuredto couple a first spacer to at least one of: (i) a lateral side and (ii)a medial side of the tibial baseplate such that the first spacer isdisposed between, and is configured to maintain a set minimal distancebetween, the proximal end of the tibia and a distal end of a femur whenthe tibial baseplate is seated on the resected surface at the proximalend of the tibia and the first spacer is coupled to the tibialbaseplate.
 3. The baseplate of claim 2, wherein the first couplingcomprises at least one of a first recess and a first process.
 4. Thebaseplate of claim 3, wherein the first recess comprises an elongatedgroove, wherein the first process comprises an elongated process, andwherein the first coupling is configured to couple with the first spacerand to guide the first spacer across the second surface of the tibialbaseplate in substantially an anteroposterior direction.
 5. Thebaseplate of claim 1, wherein a catch is disposed at an anterior end ofthe baseplate.
 6. The baseplate of claim 1, wherein the baseplatefurther defines a fastener opening that extends through the firstsurface and the second surface of the baseplate.
 7. The baseplate ofclaim 1, wherein the baseplate further comprises a tensioner couplingthat is coupled with a tensioning device that is configured to couplewith a femur such that when the tensioning device is actuated, it variesa distance between the tibia and the femur.
 8. The baseplate of claim 2,further comprising a trial tibial component, wherein the trial tibialcomponent couples with the first coupling.
 9. A tibial baseplate,comprising a tibial baseplate having a first surface and a secondsurface that is substantially opposite to the first surface, the firstsurface being configured to be seated on a resected surface at aproximal end of a tibia, wherein the tibial baseplate comprises a firstspacer coupling that is configured to couple a first spacer to at leastone of: (i) a lateral side and (ii) a medial side of the tibialbaseplate such that the spacer is disposed between, and is configured tomaintain a set minimal distance between, the proximal end of the tibiaand a distal end of a femur when the tibial baseplate is seated on theresected surface at the proximal end of the tibia and the spacer iscoupled to the tibial baseplate.
 10. The baseplate of claim 9, whereinthe first spacer coupling comprises at least one of a first recess and afirst process.
 11. The baseplate of claim 10, wherein the first recesscomprises an elongated groove, wherein the first process comprises anelongated process, and wherein the first spacer coupling is configuredto couple with the first spacer and to guide the first spacer across thesecond surface of the tibial baseplate in substantially ananteroposterior direction.
 12. The baseplate of claim 10, furthercomprising the first spacer, wherein the first spacer comprises a spacerthat includes at least one of a second process and a second recess thatis configured to mate with the first spacer coupling.
 13. The baseplateof claim 10, further comprising the first spacer, wherein the firstspacer comprises a retractor having two contact surfaces that areconfigured to be selectively forced apart to maintain the set minimaldistance between the proximal end of the tibia and the distal end of thefemur when the tibial baseplate is seated on the resected surface at theproximal end of the tibia and the retractor is coupled to the tibialbaseplate, and wherein a first of the two contact surfaces of theretractor comprises at least one of a second process and a second recessthat is configured to mate with the first spacer coupling.
 14. Thebaseplate of claim 9, further comprising a trial tibial component,wherein the trial tibial component couples with the first spacercoupling.
 15. The baseplate of claim 11, further comprising a secondspacer coupling that runs substantially parallel to the first spacercoupling.
 16. The baseplate of claim 15, further comprising: the firstspacer, the first spacer being coupled to the first spacer coupling; anda second spacer, the second spacer being coupled to the second spacercoupling.
 17. The baseplate of claim 16, wherein the first spacer istaller than the second spacer such that the first spacer and the secondspacer are configured to maintain different sized gaps between (i) theresected surface and a portion of the distal end of the femur thattouches the first spacer and (ii) the resected surface and a portion ofthe distal end of the femur that touches the second spacer when thetibial baseplate is seated on the resected surface at the proximal endof the tibia and the first spacer and the second spacer are coupled tothe tibial baseplate.
 18. A tibial baseplate, comprising a tibialbaseplate having a first surface and a second surface that issubstantially opposite to the first surface, the first surface beingconfigured to be seated on a resected surface at a proximal end of atibia, the tibial baseplate comprising: a first spacer coupling that isconfigured to couple a first spacer to a lateral side of the tibialbaseplate such that the first spacer is disposed between, and isconfigured to maintain a set minimal distance between the lateral sideof the tibial baseplate and a lateral side of a distal end of a femurwhen the tibial baseplate is seated on the resected surface at theproximal end of the tibia and the first spacer is coupled to the firstspacer coupling; and a second spacer coupling that is configured tocouple a second spacer to a medial side of the tibial baseplate suchthat the second spacer is disposed between, and is configured tomaintain a set minimal distance between the medial side of the tibialbaseplate and a medial side of the distal end of the femur when thetibial baseplate is seated on the resected surface at the proximal endof the tibia and the second spacer is coupled to the second spacercoupling.
 19. The baseplate of claim 18, wherein the first and secondspacer couplings run substantially parallel with each other at thesecond surface of the tibial baseplate, and wherein the tibial baseplatedefines a keel punch guide which includes a first wing that isconfigured to extend over a lateral portion of the proximal end of thetibia and a second wing that is configured to extend over a medialportion of the proximal end of the tibia when the tibial baseplate isseated on the resected surface at the proximal end of the tibia.
 20. Thebaseplate of claim 19, further comprising a trial tibial component,wherein the trial tibial component couples with the first spacercoupling and the second spacer coupling.